727 Early high sink rate crashes
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Thank you Tee Emm
I agree with all you say and hope these posts can be helpful. The 737 is my 3rd Jet and it has taken 700hrs before I could land it to my own satisfaction.
Current, so I know of which I speak. Twitchy Captains still out themselves by the bouncing of the right leg.
I agree with all you say and hope these posts can be helpful. The 737 is my 3rd Jet and it has taken 700hrs before I could land it to my own satisfaction.
Current, so I know of which I speak. Twitchy Captains still out themselves by the bouncing of the right leg.
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Agreeeing with many of the coments above I woul like to add my personal opinion apologizing for my lack of command in english. One must take into consideration the swept of the 727 wing that developped a very poor stability in lower speeds. As many of you recall swept wings develop a lot of induced drag in the low speed region flight needing to increase the angle of attack in order to develop lift (and more drag). The Vref speed is very close to the minimum drag speed and any drop (of speed) induces a further increase in drag needing a lot of power or altitude to trade (sink) to regain speed.This is called the "divergence zone' and the B727 more than any other commercial jet was prone to develop more and more drag as the approach speed decay. I read in a book that the first pilots to fly the B727 used to add some extra knots on the approach speed and this was also because of the stall speed used for certification purposes that taked into account the speed during stall in lieu of the minimum speed with still leveled flight. The pilots that I flew with at that time used to joke that approach speed was "Vref plus two" where 2 means 2 fingers - figure what is two fingers on an analogic IAS... I flew some 6.000hours on the 727 (-100) either as copilot and later as a captain. I enjoyed a lot this machine and consider that it has been my jet handling school for all other aircraft that I flew since then. The combination of these handling carachteristics with the poor engine accelerationn and the lack of previous jet experience of the former captains of the 60's - early 70's probably have been the main cause of many of these accidents and the option to ban the Flaps 40 configuration landing might have been the way to deal with that. This is just my opinion, of course.
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After the 1965 UAL sink rate crash at Salt Lake City, some airlines made flaps 40 optional on the 727. My airline, TWA, blocked out flaps 40.
I've got a lot of time in both the 727-100 and -200 (more in the -200 by far). I've never heard of the "burst of power" method.
I've got a lot of time in both the 727-100 and -200 (more in the -200 by far). I've never heard of the "burst of power" method.
I only "wrenched" the Boeing at EAL, but we didn't block out Flaps 40. A couple of times Captains thought it would be nice to let new FOs try a 40 Flap landing. Perhaps, that's why my back hurts in older age. That and the ejection sequence.
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GF
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Flew the 727 extensively, and in operations way beyond the scope of regular airline operations (airshows, formation flying, instruction in the aircraft), including post-maintenance test flying with speeds down to 96 knots to test the stick shakers. F30 and F40 landings. F40 did require a very different landing technique, quite like a turbo-prop flare, with much later power reduction and more developed flare. Abnormally high rates of descent were not a feature of F40 approaches. F40 restriction in many operations was simply noise-related. landing technique could vary between pilots, though conventional landings were easily achieveable, if finely judged, though the late push and roll it on method was easy to do and reliably produced beer-winning results.
As previously mentioned, landing performance, without NLG brakes, could be dramatic...not much over 500m at very light weights.
Due respect had to be made of the lengthy spool-up time for the engines, but considering this, and flying at book speeds, safety was never an issue. High rates of descent could be developed, but were due to lack of anticipation by the pilot, usually resulting in getting a bit slow (typically in the flare) and continuing to raise the nose and letting the 35-odd degrees wing sweep generate a lot of drag, while reducing thrust to land...always a filling-popper.
The whole 'unrecoverable deep stall thing is a myth'. Recovery from the stall could be protracted, granted, but to get there in the first place you would have to have been completely insensitive to the developing problem, starting with the heavy aft elevator input required and pronounced buffet.
It was a fantastic thing to fly, particularly where you had a day out doing visual approaches, and would reward planning and skill. Equally, if you flew like a moron, it showed you up.
TM
PS The comment relating to high climb angles being a result of the T tail is sheer bollocks and ignores basic thrust to weight considerations.
As previously mentioned, landing performance, without NLG brakes, could be dramatic...not much over 500m at very light weights.
Due respect had to be made of the lengthy spool-up time for the engines, but considering this, and flying at book speeds, safety was never an issue. High rates of descent could be developed, but were due to lack of anticipation by the pilot, usually resulting in getting a bit slow (typically in the flare) and continuing to raise the nose and letting the 35-odd degrees wing sweep generate a lot of drag, while reducing thrust to land...always a filling-popper.
The whole 'unrecoverable deep stall thing is a myth'. Recovery from the stall could be protracted, granted, but to get there in the first place you would have to have been completely insensitive to the developing problem, starting with the heavy aft elevator input required and pronounced buffet.
It was a fantastic thing to fly, particularly where you had a day out doing visual approaches, and would reward planning and skill. Equally, if you flew like a moron, it showed you up.
TM
PS The comment relating to high climb angles being a result of the T tail is sheer bollocks and ignores basic thrust to weight considerations.
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737-800 and 727-200 comparison.
727 w/flaps 30 would be similar to a 737-800 with flaps 35(not as slick as F30, not as bad as F40).
727 w/flaps 40 would have more drag than a 737 w/Flaps 40.
A previous post said it best - flap 40 landings are more like a turboprop, the power stays set until the landing attitude is set, or almost set.
Lots of silly, made up, 727 landing techniques. The worst was the Captain(R.A.) that used to stand the throttles at mid range until the plane touched down. In ground effect I've watched the airplane accelerate. Beyond dumb.
New FO's would ask what technique I use - "power starts coming back at 10', idle before touchdown. I don't recommend you do that until you're more comfortable with the airplane. Don't get slow, keep the power steady until right before touchdown. As you get experience you'll realize you can reduce the power sooner."
It was less forgiving then the 737NG/757/767/777 but it wasn't some monster with three heads. Touchdown smoothness was very similar to a A300. You'd think you had it nailed and the plane would say - "no, not quite good enough." Drift and crab are easy ways to reduce the 'quality' of the touchdown to a degree more severe than the 737NG/757/767/777 punish you for lack of perfection.
727 w/flaps 30 would be similar to a 737-800 with flaps 35(not as slick as F30, not as bad as F40).
727 w/flaps 40 would have more drag than a 737 w/Flaps 40.
A previous post said it best - flap 40 landings are more like a turboprop, the power stays set until the landing attitude is set, or almost set.
Lots of silly, made up, 727 landing techniques. The worst was the Captain(R.A.) that used to stand the throttles at mid range until the plane touched down. In ground effect I've watched the airplane accelerate. Beyond dumb.
New FO's would ask what technique I use - "power starts coming back at 10', idle before touchdown. I don't recommend you do that until you're more comfortable with the airplane. Don't get slow, keep the power steady until right before touchdown. As you get experience you'll realize you can reduce the power sooner."
It was less forgiving then the 737NG/757/767/777 but it wasn't some monster with three heads. Touchdown smoothness was very similar to a A300. You'd think you had it nailed and the plane would say - "no, not quite good enough." Drift and crab are easy ways to reduce the 'quality' of the touchdown to a degree more severe than the 737NG/757/767/777 punish you for lack of perfection.
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gf:
The FAA or NTSB recommendation was to use flaps 30 normally, and only use flaps 40 if necessary. TWA elected to block out flaps 40. So far as I know most carriers did not. We flew National 727-200s one or two summers on a summer/winter exchange. They did not have flaps 40 blocked.
I only "wrenched" the Boeing at EAL, but we didn't block out Flaps 40. A couple of times Captains thought it would be nice to let new FOs try a 40 Flap landing. Perhaps, that's why my back hurts in older age. That and the ejection sequence.
Comparison has been made on this thread between the 727 and VC10. One thing that has always struck me, as SLF, is that the VC10 doesn't really flare on landing - it seems to point the nose at the threshold and level up just before touchdown This video shows what I mean
I presume that they don't do this just because the passenger seats in RAF VC10s face backwards. Is it in fact quite different from a 727? Apologies for thread drift
Tri Motor and Misdagain are completely correct.
Deep stall was never an issue.
And there were loads of silly landing techniques and myths as to why.
You had to watch you sink rate carefully, if you let a high rate develop you did need power and lots of it quickly.
However, you could flare and land normally with idle power, and this, as with most jets is optimal.
F40 was blocked at my Airline and most US operators.
Deep stall was never an issue.
And there were loads of silly landing techniques and myths as to why.
You had to watch you sink rate carefully, if you let a high rate develop you did need power and lots of it quickly.
However, you could flare and land normally with idle power, and this, as with most jets is optimal.
F40 was blocked at my Airline and most US operators.
EAL's 727s weren't blocked at 30 and Flaps 40 landings were at the discretion of the captain except at KEYW where 40 was mandatory. 4,800 feet of LDA. The standard was 30, however.
GF
GF
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IGh:
Maybe someone canfind an old Recurrent Train Bulletin describing DATE of the INITIALMODIFICATION that blocked B727's F40 [my guess is that modification was a FUELCONSERVATION measure after the price of fuel doubled between April and Augustof 1979 (????)].
Below is a none-too-good photo of the flap lock-out block. Note it is held in place with two screws. This photo is a clip from a photo of me and a good friend en route in a TWA 727-100 in the early 1970s, if memory serves me correctly. I believe itwas 1972.
Also, I am not sure the FHB would have ever shown the block. If the FHP you have is complete check the flight profile illustrations. They would show selection of Flaps 30 as final landing flaps.
Then I checked an old TWA FHB for their B727's, pagedate May 1977, Controls & Indicators, still shows the F40 position (withoutany mention of a Gate-Blocker for F40).
Maybe someone canfind an old Recurrent Train Bulletin describing DATE of the INITIALMODIFICATION that blocked B727's F40 [my guess is that modification was a FUELCONSERVATION measure after the price of fuel doubled between April and Augustof 1979 (????)].
Also, I am not sure the FHB would have ever shown the block. If the FHP you have is complete check the flight profile illustrations. They would show selection of Flaps 30 as final landing flaps.
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IGh:
The Detroit "swan dive" happened long after TWA blocked out Flaps 40. I checked out in late 1968 and the block was already in place. It wasn't when I went through F/O school on the 727 in late 1964.
I just verified with another retired TWA pilot that the block was in place by late 1968. I also recall being instructed that it was because of the 1965 UAL KSLC accident and, additionally, Flaps 40 was a lot of drag for the early stages of an ILS missed approach.
When fuel savings became an issue the company reduced Mach cruise by a fair amount and added a performance monitor. The also changed the climb schedule.
I was still flying the 727 when Captain Gibson made his dive over Detroit. Nothing was mentioned about it to any recurrent ground school or simulator session I attended. I flew that airplane shortly after it was returned to service. The ripples on the lower aft fuselage were "interesting" to say the lease.
Thanks -- I had no doubt that line-pilots heard their Ground School Instructors spread that rumor about the company's MOTIVE for blocking F40 [recall that various airline Ground Schools propagated the "Boeing Scenario" (a rumored high altitude CRZ configuration) after the 4Apr79 mysterious inflight upset of a B727-31]. Human instructors were entertaining (now pilots get CBT without the entertaining ad lib's of a human ground school instructor). [The Boeing Rep' at at TWA's K.C. HQ related to me the the "Boeing Scenario" began right there in K.C., over the back-fence, and was then reported back to Seattle. Rumor can force investigator-err, when desired by that once overpowering manufacturer.]
I just verified with another retired TWA pilot that the block was in place by late 1968. I also recall being instructed that it was because of the 1965 UAL KSLC accident and, additionally, Flaps 40 was a lot of drag for the early stages of an ILS missed approach.
When fuel savings became an issue the company reduced Mach cruise by a fair amount and added a performance monitor. The also changed the climb schedule.
I was still flying the 727 when Captain Gibson made his dive over Detroit. Nothing was mentioned about it to any recurrent ground school or simulator session I attended. I flew that airplane shortly after it was returned to service. The ripples on the lower aft fuselage were "interesting" to say the lease.
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Thanks.
As for the flap 40 block. It sounds like one or maybe a few companies did it way back when after an accident or two but most did it for noise abatement much later.
The Raisbeck hushkit mod has a maximum of 28° flap along with a shorter full extension for the slats. Not sure about the Kruegers.
