Miles O’Brien, pilot and blogger, has a fascinating two part blog called “The ‘Coffin Corner’ and a ‘Mesoscale’ Maw”, which has been widely reprinted by Reuters. Its broad subject is what happens inside the narrow aerodynamic envelope that a modern jetliner inhabits for economic reasons. It is near its maximum altitude where it must fly fast to maintain lift, but at which it has little or no reserve power in its engines, where the distance between stalling and overstressing the airframe can be only 25 knots wide. This was the situation that Air France Flight 447 must have been on the fateful night it disappeared. O’Brien writes:
Because there are relatively few air molecules passing over the wings, they need to be moving faster to generate enough lift to keep the plane at altitude. They will stop flying (stall) at a much higher speed (true airspeed) than they would on approach to an airport at sea level. At the other end of the safe speed spectrum is the sound barrier. The wings on an airliner like the A-330 are not designed to break the speed of sound. Venture toward Chuck Yeager country and an airliner will begin buffeting. And as altitude increases, the buffet speed (the sound barrier) decreases (once again the dearth of air molecules is to blame). … AF 447 was flying through the eye of a speed needle only about 25 knots (28 mph) wide.
But don’t worry. Passengers fly through this needle-eye all the time. All is well, O’Brien says, as long as the instruments are functioning on the aircraft and no extreme weather is encountered. But what happens if neither of those two conditions hold true? The first factor he examines is the weather, quoting Tim Vasquez’s meteorological analysis which the Belmont Club had also linked to earlier. That far out into the ocean the pilots would have been operating in an information-poor environment with respect to the weather. Their pre-takeoff weather briefings will have been outdated. They would be reliant on their instruments “akin to a blind man with a cane” to know what they were up against.
Did the Air France crew spot a gap in that first line of storms that turned out to be a “sucker hole” – sending them into a box canyon of violent storm cells? Maybe. If they could have seen the full depth and intensity of those storms, would they have changed course to avoid it? Hard to imagine they would say, “Steady as she goes…”
He will continue in the second part, which I suspect, will focus on the other factor: the airplane instruments, the length and reliability of the cane. O’Brien’s wonderful piece brought home to me how unavoidably dependent aviation is on information. Information about the plane’s airspeed, altitude, attitude and condition; information about the outside environmental variables. Whether derived from the pitot tubes, the onboard radar or downlinks, an airplane flies on information as much as lift. That should be especially true for a fly-by-wire aircraft whose automated systems play such a large role in controlling the plane. Unless the data flight records are retrieved we’ll never know what the doomed pilots realized in the last four minutes of their lives. What did they realize, but realize too late?
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Can someone explain to me why the U.S. Navy is dropping listening devices to try to find the black box? Does it emit a tracking beep or something?
Yes, that’s it exactly NahnCee.
But only for about 30 days, then each battery independently fades out.
Very interesting post. If “extreme weather” is a factor in this disaster, we had better brace ourselves for the green/left accusation that it’s our fault for emitting so much CO2. Ready, steady, go…
O’Brien’s wonderful piece brought home to me how unavoidably dependent aviation is on information. . . . Whether derived from the pitot tubes, the onboard radar or downlinks, an airplane flies on information as much as lift.
That comment could serve as a metaphor for our society. Only instead of getting vital info from avionics, we’re stuck with the MSM.
So many things have a narrow range of viability these days. The cash flow equation of airlines today is very precarious as well, and is negociated only by careful tracking of critical information, in that case seat reservations, to keep all the seats occupied, or nearly so, on all flights.
On one hand it means things are being run at peak efficiently, on the other hand it does not take much to go from smooth running to disaster. In some way we are all acrobats, and we can all fall, sometimes literally!
Wretchard said,
“Its broad subject is what happens inside the narrow aerodynamic envelope that a modern jetliner inhabits for economic reasons. It is near its maximum altitude where it must fly fast to maintain lift..”
Along these lines is an interesting aeronautical engineering tidbit: The Lockheed U-2 (NASA calls them “ER-2″) actually cruises in the corner of its flight envelope, i.e. just below its altitude ceiling, just below Mach-1 (it uses an unswept subsonic wing) and just above its stall speed. I emphasize the last point: the ER-2 cruises a gnat’s whisker below Mach-1 while at the same time it’s a gnat’s whisker above its stall speed. That’s about as balls-out as an airplane can get. The U-2/ER-2 flies in an environment not unlike what an airplane would experience flying near the surface of the planet Mars, i.e. near Mach-1 and stall speed at the same time. With a Mars airplane, the aeronautical engineering can get really weird because the Mach and Reynolds numbers don’t conincide like they normally do so a conventional airfoil shape is inappropriate. I have no clue how Kelly Johnson dealt with this when he designed the U-2.
Kelly Johnson was one of the brightest aeronautical engineers who ever lived. He designed the SR-71, the U-2, the F-104 and the P-38. All four planes were really hot and also very scary to fly. Even the venerable P-38 was scary because the pilot had to invert the plane before bailing out, otherwise the elevator might cut him in half.
the press said that the pilot was experimented on such wheather conditions
According to the Beeb, the plane’s vertical stabilizer was recovered earlier today:
http://news.bbc.co.uk/2/hi/americas/8089917.stm
Wretchard mentioned the “coffin corner”. One of the reasons why aeronautical engineers seldom fly in helicopters is this region in the helicopter’s flight envelope called the “dead man’s zone”. The dead man’s zone is defined by the altitudes and airspeeds below which a helicopter can not autogyro (death is assured). A helicopter almost always flies through the dead man’s zone during take off and landing.
Helicopters very bad … don’t like helicopters.
After using aircraft instruments for years I recently came to appreciate the subtle aspects of their design. I got hold of an old WWII vintage altimeter and decided to see if it still worked. Nope, compared to the one in the airplane it was way off. But later I realized that the WWII vintage one had not one but two scales on the face, an inner scale for thousands of feet and an outer one for hundreds of feet – unlike the usual altimeter that has one set of numbers around the outer edge for both. It made it much harder to read if you were not used to it, but as it turned out it was pretty accurate. An instrumentation expert friend of mine told me that the unusual design was likely an attempt to avoid patent restrictions. I wonder how many pilots using those things misread their altitude by a thousand feet or so.
Then I had to replace a bad tachometer and initially tried one out made in China. Looked okay, worked okay, but when I tried it out I found a design flaw. The numbers were arranged around the outside of the dial rather than the inside, with the calibration marks inside the numbers. This looked okay at first glance but the design meant that the needle was much shorter and therefore small changes in RPM were not observable. You could not do a run-up check before flight. I bought a new American made tach.
Years ago a Boeing 727 crashed while landing at night. Investigation showed that the generators had failed and that the battery switches on that version of the airplane had been moved to a spot normally occupied by the switches for some nonessential equipment. So when last generator failed on final approach the crew proceeded to go through the checklist to shut down nonessential systems and turned off the battery power as a result.
People figured out all of this stuff years, decades ago, and no one seems to have written it all down. The worst Coffin Corner is in the mind.
Unless black boxes float free of the aircraft when it crashes it is at the bottom of the sea inside the fuselage. It is unlikely that it would be found in that case, as it you would need a sonar blind man’s cane to find it – good luck. Also possible that it sank in such a deep part of the mid Atlantic trench that the pressure at depth crushed it beyond recognition, much less recovery.
Eggplant,
“Helicopters very bad … don’t like helicopters”
Shame on you!!
12) There is potential for them to be damaged in the crash, but they have survived significant impact forces, and also survived the type of depths being discussed here. (2.5 – 12 K feet). They will be emitting a sonar signal, which probably has a range of several miles. The location of box is within a relatively small area (for this type of search) because they have the wreckage to use as a starting point (after adjusting for drift).
They talk about the technical details but they don’t say anything about the decision making process, which is the hard part. Getting a change of clearance in oceanic airspace is sometimes quite difficult. HF radio is pretty unreliable, you might not be able to get any response, and if you can there may be several other flights trying to talk to the operator, and you can’t get a word in edgewise.
From the track overlaid on the weather it looks like they deviated north to avoid some cells. I have not seen any indication they got a clearance, but that wouldn’t be critical in this case. Getting a change of altitude would be much harder and I doubt they would have changed altitude without a clearance.
Airline pilots seem to prefer to understate the level of turbulence a little bit, so if they were reporting “strong” turbulence I’ll bet it was getting pretty hairy. I have been flying a straight-wing jet for some years but before that I flew 727s a bit. As I remember the caveat with “buffet speeds” (the high/low speed buffet chart, which gives you the spread) is that the numbers are only good in smooth air, and you need an additional margin in turbulence. I still have the manuals but they are buried in storage.
A high school classmate of my father’s went on to be a bush pilot in Alaska, and later fly for Alaska Airlines. Asked how he survived so long, he said, “If the weather is bad, turn around.” A 180 degree turn should always get you out of trouble. After all you were just flying there and it was OK. But it has to be executed soon enough. As O’Brien points out, if things get really bad, you can’t even turn anymore. Stall speed increases in a level turn so you may have no choice but to cross your fingers and pray.
exhelodrvr,
You’re obviously a braver man than me.
What sort of helicopters did you fly?
I don’t think that makes me braver.
Sikorsky Sea Kings (H-3s).
Is that route that the Air France jet flew normally a very dangerous one? If so, then perhaps something needs to be done to get more timely meteorological information to the pilots as quickly as possible so that maybe they could make some course adjustments to try to avoid the worst of those kinds of weather cells.
fred asked:
“Is that route that the Air France jet flew normally a very dangerous one?”
I don’t believe it is. This accident was probably due to some sort of equipment failure. We’ll know better after they recover the black boxes.
I asked before but does the Airbus control system have artificial intelligence for equipment failure built into the computers that either cant or is hard to override?
I read that the Hudson Flight almost went more sour because the computer thought it was supposed to save the engines it thought had had oil pressure failures, but the pilot wanted to save the airplane.
Eggplant and exhelodrvr; Helicopters very good. Especially HU1 called “Dustoff 52″.
Eggplant: Prescribed bailout procedure for the P38 Lightning was as follows:
Put aircraft nose upwards into near stall;
Unbuckle seat belt and oxygen mask while
opening hinged canopy;
Crawl out onto stub wing between tail booms;
Stand up and pull rip cord catching parachute
in arms as you stand there;
Then execute swan dive off stub wing, between
tail booms and in front of horizontal stabilizer.
When my natural father “got his wings” at Luke, he showed a P38 to his mother and sister-in-law. The latter heard the former ask, “How do you get out in a hurry?” He replied, “You don’t.” Several months later, he didn’t. One month after that I came along.
Some of the survivors of his unit (82nd Fighter Group) can recall meeting Kelly Johnson.
Now what could that P38 do? In their case,
548 confirmed, 88 probable, 227 damaged,
sunk 9 ships, destroyed 126 locomotives and assorted rolling stock. and dive-bombed one Ploesti refinery.
Will hold their reunion here in Las Vegas in September. Senior man is now age 97, maybe the oldest living Fighter pilot?
A Messerchimitt ace flies in from Germany every year for these reunions. George had 38
victories and a Guardian Angel as he was shot down 6 times and never had to go to the hospital.
Google up their website and read some of their mission reports. Especially the one on 10 Jun 44. That consisted of flying to Ploesti with both a 310 gallon drop tank and a 1000 bomb. Release former at some point or other, release the latter at 1200 feet. Then fly out through a flak belt and say hello
to enemy fighters as you regain altitude for the trip home.
A rather small envelope that day, wouldn’t you say? Ben Mason, (age 97) just calls it
“another day at the office”. Think I don’t love those guys?
And two of their mechanics, Jake Hendrix and Olen Medley were on the deck of the Queen Mary when she sliced the Curacao in half on the way into Belfast Harbor. Olen took the dramatic photos of the collision.
And BTW: It was Kelly Johnson who more or less founded “Area 51″. Wanted a place to work on that U2 in private. Groom Lake had been used for an A-Bomb test or two and folks just naturally avoided it even though there was nothing more than normal background radiation left there.
I have been involved in some aircraft and space mishap investigations and studied many, many others.
It is never just one thing. An equipment failure is compounded by the design feature of another component or a human being’s failure to respond properly to the failure. A design feature leads to a human error. A human’s error is compunded by other errors.
The most common cause of aircraft crashes is – believe it or not – running out of gas.
And finally let me close with an old joke:
Two men board a Boeing 747 for a flight from England to New York. Shortly after takeoff the captain makes his welcoming announcement, giving them an estimated flight time to the destination.
An hour later the captain comes on and says that unfortunately they have had an engine fail and that everything else is Okay, but it will delay them getting to NY by an hour.
An hour later the captain comes on and says they have lost another engine and that the alternate airports are socked in with bad weather but no one should worry but they will be delayed getting into NY by another hour.
Two hours later the captain comes on and says they have lost another engine but that the remaining engine is a new one and is running fine and they have plenty of altitude so that no one should worry but that they would be delayed getting into NY by another hour.
At this point one of the men turns to the other one and says “You know, if we lose that last engine we will be up here all night!”
It has been a good many years since I earned my living as a pilot with a major US international flag carrier (now deceased), but I was paid by the hour, and I never hesitated to deviate as far as necessary to avoid dangerous thunderstorms. They certainly didn’t pay us extra to penetrate those storms. Even back in those days we had pretty good weather radar, and I never even got close to getting into a “sucker hole.”
During my early career Captains had full discretion as to their fuel loads, and any extra fuel we wanted was provided no questions asked. After the fuel crises of the ’70′s we started getting arguments from dispatchers, as extra fuel = more weight = more cost. I won every one of those arguments, as I would not take a flight that did not have the amount of fuel that, in my judgment, was necessary.
The following is pure speculation, but here it is for what it’s worth. I don’t know what Air France’s policy is in this area, but could it be possible that the crew had insufficient fuel to deviate as far from their flight plan as required to safely traverse the dangerous weather? In my career, I have deviated hundreds of miles on a few occasions for that purpose.
All too frequently in the past, safety precautions have been written in blood. Whatever the reasons for that crash, I hope they are learned so that the lessons can be applied in the future.
fly-by-wire, autopilot responding to sensors gone haywire –i’m only a layperson, but pilot son sez –get in bad trouble fast.
The Miles O’Brien comment (and those of Tim Vazquez on the weather) are both fascinating and chilling –and admirable for their clarity. These guys (like most posters here, e.g. pilots) really know their stuff. People who know their stuff almost always can explain it well to the lay audience. From which it follows: if you are confused by an “explanation” it means either the person does know the stuff but won’t share it; or doesn’t know the stuff. Usually the former case describes politician, the latter case describes journalists.
All done.
26: When I was a graduate student somebody told me that if I can’t explain something to a five year old, then I probably don’t really understand it.
Has anyone seen the 2nd half of O’Brien’s story? Don’t know if it’s up yet but I can’t get it on that website.
24 Cap’n Eddie
All too frequently in the past, safety precautions have been written in blood.
I’ve heard that called “tombstone technology.” I have a cousin who is a pilot with US Airways– he’s said the same things as you have about the importance of an adequate fuel supply.
Dave,
Thanks for the comments about the P-38. I’m an unabashed fan of the SR-71 and the P-38. As I’m writing this, there’s a poster of an SR-71 in front of me and model of one to my left. I once had a poster of P-38s flying in formation (got it from the Nut Tree). What a hot airplane!! Sadly, my P-38 poster dry rotted and went into the trash. An interesting bit of trivia: Chuck Yeager did NOT like the P-38. He considered twin prop aircraft intrinsicly flawed as fighter planes and the P-38 no better than the hapless Me-110. Yeager is one of my heros but he was dead wrong about the P-38. He could not get outside of his bias towards the P-51 (another fantastic plane). If I had the money of Bill Gates, I’d buy a P-38 and spend all my waking ours screaming around in it and making a public nuisance out of myself.
Dave, you also mentioned that helicopters are very good. Sorry, I can not get into helicopters. Helicopter accident statistics show that they’re dangerous. Their flight envelope is obviously dangerous. Their basic design is like something Rube Goldberg would have invented and helicopters have all those opportunities for single point failure. I know that there are unique missions that only helicopters can perform and fortunately there are brave men and women who are willing to fly them.
I’ve spent a lot of time as a passenger in choppers. Something fun we used to do flying out to drlg rigs and back, was when we’d have somebody new –that didn’t know the pilot –logged in, the pilot would sit in back, like a rig regular. We’d wait a few minutes and then start bitching about the pilot being late –then actual pilot would fake lose his temper and clamber into the pilot’s seat barking “Hell, I bet i can fly this SOB if i try!” We’d say “go ahead, then, give ‘er a try” and watch the newbie turn green –and try to get out usually –we’d hold him in and say “what the hell, man, you wanna live forever?”
That P-38 really shone on those looong over-water Pacific Theater missions. If getting to the fight was a problem, the P-38 was great –and a spare engine to boot! And for warbird looks, “wow!” The field in San Marcos where my kid took his lessons was rebuilding one of ‘em –but it had a big chin blister for photorecon or radar or something which broke up the lines, poop.
Yeager was a dyed-in-the-wool dogfighter and an engine master mechanic to boot –i can see where he’d regard that extra engine as a big impediment –acceleration, roll-rate, things like that that –that a single engine could just ride its torque and do like a bird.
I wrote an article on a special P-38 some 10th Recon guys built up out of a shot up airplane and wrecked parts. It was in the May 2001 issue of Air Classics.
It was so cool to think about doing that, putting together a “hot rod” P-38 with the latest model engines and turbosuperchargers on a stripped early model airframe. With the guns, armor plate, and cameras taken out it climbed like nothing else around. A proud RAF pilot in a new Spitfire Mk.8 challenged that old Lightning to a drag race one day. It was no contest, like an F-4 and an SR-71 racing.
Buddy:
When I still lived in Calif they showed video of a student pilot with a Hughes 260 who got tired of waiting for the instructor and took off by himself after only a couple of hours of dual instruction under his belt.
First thing the novice pilot did was knock the tail rotor off and very soon after that the cameraman lost interest in filming and concentrated on escaping the flying debris.
#24, Capn Eddie,
Thank you for your personal account of a way of thinking about weather and deviating from it if necessary. And requiring extra fuel for such contingencies. I rather suspect that airlines have, because of fuel and other costs, have gone in a direction that could be unsafe. I’m not an aviator, and this seems to be an aviator’s forum on this thread (I have no problem with that, and I’m learning some things too), but I do appreciate it when someone states that we need to be able to explain something so that a five-year old can understand it.
I don realize that nothing definitive is going to be revealed unless and until the black boxes are recovered. Also, those boxes may never be recovered, since the depths of the ocean in that area are formidable for discovery and recovery. If the boxes are still in the fuselage and the fuselage is in 20,000 feet of ocean, I assume that there’s really nothing that can be done?
Latest issue of Av Week quotes the Tim Vasquez analysis linked to here earlier.
Also it says that the A330 has 5 flight control computers, 3 primary and 2 secondary.
And it points out that an A330 of Quantas in Oct 2008 had faults in the flight control system that led to uncommanded climbs and descents and a rapid loss of altitude. BUT that airplane had a different system on it than the one that was lost, made by Northrop Grumman. The A330 for Flt 447 had a system made by Honeywell. So even if the airplane was French the flight control system was American.
By the way, the article says that fuselage of the A330 is aluminum, with only about 10% composites and that the flight controls are heavily shielded as well. So a lightning strike should have not been that bad in terms of effects on composite structure.
I wonder, they never did put a four blade paddle prop on the Lightning, or did they –?
Cap’n Eddie: You go right ahead and load
all the fuel you think you might need. Working ramp/bags for a regional carrier, I
have seen a few diversions/returns when the
weather went down suddenly and all that “uneeded” fuel got consumed.
My problem, and that of the receiving BSO, was the number of bags that had to be held off
to avoid getting overgrossed for safe landing.
I always tried to (a) select bags by name so
that as few individuals as possible would be disserviced, (b) brief passengers on what was going to happen so things did not come as a surprise, and (c) fully inform receiving BSO
so that she would be prepared. All of which is not as easily done as said.
My idea of a miracle plane was one that could land with more weight than it could take off with and let a rookie First Officer land in zero-zero.
And of COURSE Scottie should get the lead out and get the Transporter Room working so we
could do away with all this airline nonsense.
Buddy Larsen: What you saw in San Marcos
was a “Droop Snoot”. Took out the guns,
altered the nose into that funny configuration, stuffed a bombardier into
resulting compartment. Droop Snoot would
then swoop in low and mark the target so
the other P38s could do “high altitude precision bombing”. (They usually omitted the “high altitude”.
The “precision” was fair to middling good—–unless the bombardier had hypoxia, in which case something or other in Northern Italy
received an unexpected load of bombs.
By The Way Larsen: How come I have to find all these things on my own? I thunk you wuz gonna be the BC eyes and ears in the Hill Country.
And you have not even mentioned our recent stunning cultural victory. In Bandera, they
have rebuilt and reopened THE SILVER SPUR, no less. Once again the good times roll while
Slim Whitman and ERNEST TUBB come forth with
“The Bandera Waltz”.
(Doug, just bring Trangbang, got plenty of beer already.)
And Buddy has not breathed a word about this. Straighten up and fly right Larsen before I gig you fer an Aggie.
Eggpllant: SR 71 story. Was originally called RS 71. LBJ kept reversing things so his version stuck.
In 1964 campaign, LBJ shot off his mouth to some of his cronies and they doubted his story
of a plane that fast. So he would show them!
Took them all out to Edwards. Blackbird took off from Area 51, took scenic route to build up speed and awed them with a couple of Mach 3 passes over Edwards.
Then landed for viewing. Couldn’t have these people out in the sun all the time, so viewing stands were arranged inside a hangar. SR71 was towed inside where the radiant heat from the skin set off the sprinkler system and drenched the whole party.
Wonder why that never made the evening news?
BTW: You failed to mention what I think was (in many ways) some of Kelly Johnson’s best work. Namely the P80/F80/T33/F94 series.
For pratical purposes it was better than the ME262, only required one of those new-fangled jet engines, was easy to learn to fly and could have been mass-produced in short order had the need arisen.
At any rate, I figure Kelly is having a good times discussing airborne aramament with John M. Browning. Sure am glad we had both of them.
Dave,
I have my own SR-71 story not unlike yours. Years ago, I was attending an air show at Travis AFB. It was announced that an SR-71B (the trainer version) was going to do a flyby. We all stopped what we were doing to watch it fly in. The pilot had the landing gear down and was flying just a little bit above stall speed. It was not very impressive and I have to admit that I was a little bit disappointed.
However this was just the teaser.
The pilot then flew around Travis AFB and came in a second time with the landing gear up. He came in just a gnat’s whisker below Mach-1, flying as low as he could. Then when he was precisely over us, he did a snap pitch up maneuver, lit both afterburners and in a deafening roar climbed straight into a cumulus cloud.
Initially, the audience was stunned silent by this amazing sight but then we all went into wild applause. It was a perfect thing of beauty.
okay, Dave, that aggie bit stung, so i went to work and found a beautiful film of America’s very first jet flight.
The Bell XP59A –Autumn of 1942.
The craft flew so smooth the instruments kept sticking –so one of the field mechanics had the bright idea to install a two dollar doorbell ringer in the dash panel –which provided enough vibration to unstick the needles. If the test pilot needed to know something, i guess he had to ring the doorbell & hope a gremlin didn’t answer.
Whenever they had to move the secret prototype along the roads they made it wear a big old wooden propeller. It already looked like an Airacobra so i’m sure that ruse worked just fine.
Here it is (Go Longhorns!):
http://www.videosift.com/video/Americas-First-Jet-Flight-October-1942
Richard, that business of coffin corner being only 28kt wide in an airliner is seriously exaggerated. I’m type rated on the RJs, which have similar performance numbers to a heavy, and am looking at the AFM operating speeds chart right now for the CRJ700, and it gives a maximum Mach # (Vmo) of .85 above 32000 ft. The A-330 is similar (the very fastest airliners are up around .88, but .83 to .86 is typical). The A-330 has a max cruise of 41000 ft, but normal cruise will be in the 30s. Even if they were at 41000 ft the indicated airspeed at Mach .85 is 250 kt in standard conditions. I don’t have the Airbus stall numbers handy, but the flaps up stall on a heavy is going to be somewhere in the region of 130kt, maybe 150 kt tops (being indicated airspeed, the value is constant).
So the margin above stall at max Mach# and max cruise alt is more like 100kt indicated. Plus there will be an ample safety margin between Vmo and the critical Mach # (the speed at which airflow first becomes supersonic), maybe 20 to 30 kt, before mach buffet would start. In practice the cruise is probably more like .8 for fuel economy reasons, which is a slower indicated airspeed but that means the margin below Mach crit is more, so the coffin size doesn’t change.
So “coffin corner” in an airliner is actually well over 100kt wide, not 28 kt. The 28 kt applies to airplanes like the U2 which cruise at 70000 and have a low Mach Crit.
What IS a problem at that altitude is that the low indicated airspeed (cruising at 230-250) is close to a point called “back side of the power curve” where decreases in speed require increases in power to maintain the level. If speed starts to decay, and you’re maxed out on thrust, you have no choice but to go down and convert altitude to speed. If the airplane is on autopilot and pitching up to hold altitude in this condition, and the crew is not paying attention to the decaying speed, the autopilot will take the aircraft right up to the stall warning threshold on its own. A Pinnacle airlines crash of a CRJ200 was due to just that.
Cheers
John
Correction: Vmo (velocity or speed maximum operating) should be MMo (maximum mach operating)
Great SR-71 stories, y’all. For those who missed it, here’s the famous Brian Schul “Libya” story.
Quick follow-up: Bell Aircraft was told not to let any of those Muroc (now Edwards) trainees see them fly that jet. Good trick in virtually unlimited visibility.
Bell’s Chief Test Pilot Jack Woolums had a brainstorm. Whenever he saw a training flight, he would slip on the top half of a gorilla suit, put a derby on his head, pull up alongside them and make like Groucho Marx with a cigar.
Now if YOU are a 19 year old aviation cadet in 1942 are YOU going to report;” There I was at 18000 feet when suddenly alongside me was an airplane without a propeller being flown by a gorilla wearing a derby and waving a cigar.”?????????????
And if any spies are in the vicinity are they going to believe that tale??????????
And I just happen to know one of the guys who
obligingly failed to see that apparition.
He was busy strafing a Japanese Cruiser in the Mojave Desert at the time.
Buddy, if you can find a picture of the “Muroc Maru”, I’ll call off Beevo and
restore your Teasip standing.
Seriously though, reopening the old Silver Spur Dancehall to go with the current Silver Spur Dude Ranch is a bit newsworthy, I would say.
John K,
Thanks.
W.
I’ll look for it, Dave. That dancehall, that’s where the Aggie walked in carrying a fresh hot steaming cow pattie dripping through his fingers, and announced “Hey, y’all, look whut I almost stepped in!”
Not seeing that apparition, that’s a helluva thing to not see, and a helluva non story to not tell!
Whether derived from the pitot tubes, the onboard radar or downlinks, an airplane flies on information as much as lift. Information — the driving force behind so much we do, flying or otherwise. No matter how far we’ve come in terms of being able to get and process information it always seems we are far away from being where we want to be in terms of information. That sucker hole in the clouds could be a literal or it could be a supposedly solid stock with a low price.
Re helicopters, I taught with a guy who attended an avionics/aviation engineering school. On a trip we took together he noted the same about helicopters it’s a miracle they fly.
As far as finding the blackbox, I am quite certain it will be found this is good practice for the Navy in locating vital things on the ocean floor. A book by the name of Blind Man’s Bluff is a fascinating read on the underwater skirmishes we fought with the Soviet Union — in the areas of subs penetrating Soviet waters, locating critical items (such as lost submarines both US & Soviet), and espionage.
Buddy,
Thanks for the link to the Brian Schul story. It’s clear that Schul loved his SR.