View Full Version : 737 Max - are the regulators wrong?

blind pew
1st Mar 2020, 14:26
Is the increasing elevator feel with increased angle of attack a useless hangover from the first world war? If so the archaic regulators and their disciples responsible for the worse ever peace time aviation scandal.
My revised 1969 B.L.A.C instructor's manual has 4 stall symptoms; falling airspeed, decreasing effectiveness of controls, buffeting and aircraft sinks.
My 1999 B.G.A manual has eight including probable changed effectiveness of elevator.
But none mentioned increased stick force.
I now fly paragliders whose pitch control force increase towards the stall by design but it hasn't stopped me accidentally spinning a wing – twice.
In 1971 after passing my IRT I had ten hours to burn on the flying doctor widow maker; the Beech Baron. Over the new forest I did a clean, power off stall which ended up inverted having completed a half flick roll before I centralised the controls.
40 years later I similarly ended up inverted at 200ft flying a Grob glider near the Cape Gliding Club S.A. whilst demonstrating French mountain soaring techniques. Again without any noticeable change in stick force.
In 1972 my best mate mistakenly retracted the slats and despite the stick shaker and stick push going he died. One of the accident investigators stated that the simulator pitch control wasn't the same as the aircraft. We hadn't flown approach to the stall in real life as it was deemed too dangerous after a Trident was nearly lost.
A couple of years later a new boy, whilst sir was in the loo, selected slats out whilst in the Clacton hold around 25,000ft. The aircraft stalled (above mach limitation) and only recovered after careering through several other aircrafts flight paths into lower air.
A couple of times I heard brief stick shakes during approach in turbulence. Stick force not mentioned.
I was in the classroom when our DC10s were grounded after Chicago when the engine fell off taking out two of the hydraulic systems allowing the slats on that side to retract. No cockpit indication nor slat locking device and the wing stalled.
We were only allowed to fly it with CWS plugged in so control forces were irrelevant.

I was one of the first lot of pilots on the Fokker 100 with full time thrust stall protection according to our books. Two crews both doing a split arse visual approaches into Nice at low level had the stall warning go. No one noticed the stick pressure and why would they in a descending turn. The manuals were re written.
A mate in a big Boeing levelled off in descent...stick shaker reminded him to engage autothrottle.
AF447...glider pilot operating a one man band as captain chasing crumpet and senior first officer a wet paper bag (management doing a 90 day currency trip). How relevant increased stick force?
Nor with the Airbus test pilot sinking one in the Golf de Lyon.

Another mate who was squadron test pilot on the Gnat got a loop wrong due to alcoholic haze..high G, high speed buffet saved him but burnt some pasture.

I can go on and my Mrs often says I do but in all of my flying increased stick force has never alerted me to an approaching stall.
Maybe it became fashionable and sticking two cheap springs on the stick whose force increased the more they were stretched set the normal but imho it is a complete waste of time on a large transport aircraft.
So why fix a problem which doesn't exist? And with a bodge at that!

1st Mar 2020, 15:17
It's a meassurment method for static stability margin.
Not a stall identification issue. Not a feel issue. A positive stability margin not large enough issue.

As the CG moves aft, it reaches a point where the stick force per knot drops to zero, then reverses. This location is called the neutral point. The difference between the actual CG location and the neutral point is called the static margin. With a CG forward of the neutral point, an airplane has a positive static margin and positive static longitudinal stability. At a CG aft of the neutral point, an airplane has a negative static margin, is statically unstable, and requires some form of augmentation to be flown with an acceptable workload.

1st Mar 2020, 16:12
An interesting exercise in logic. You cite examples where increasing stick force did not prevent a stall, including several where it was completely irrelevant, and use this as an argument not to require it. This is similar to arguing that cars don't need brakes because there have been cases where they didn't prevent a car from hitting a stationary object. I think I'll leave it at that as i have better things to do with a Sunday afternoon.

1st Mar 2020, 16:21
On the 737-Max at high angle of attack air flows from over the top of the huge engine cowling and continues to flow over the top surface of the wing due to its location in relation to the wing leading edge.
Had the engine been located lower this would not happen - air would slip bellow the wing. Having been located so high it becomes part of the wing lifting surface far ahead of the wing itself.
That moves neutral point towards front and reduces static stability margin.

1st Mar 2020, 16:21
I had to go and find my sandbag to sit through that history Pew!
Some good points made and reminders to us all of how aircraft behaved with older designs.
I would suggest that not many recently trained Pilots will ever encounter such moments, lucky for them.
I did raise my eyebrows at “captain chasing crumpet” however. To suggest so, unless factually correct, frankly does you no credit Sir and is appalling imho.

1st Mar 2020, 16:51
AF447...glider pilot operating a one man band as captain chasing crumpet and senior first officer a wet paper bag (management doing a 90 day currency trip).

I did raise my eyebrows at “captain chasing crumpet” however. To suggest so, unless factually correct, frankly does you no credit Sir and is appalling imho.

Here are a couple of appalling news reports on the subject.

From the New York Post:

Marc Dubois, the 58-year-old captain, had left the cockpit to take a nap because he had been up all night with his mistress, and returned when it was too late to avoid catastrophe.The married captain was accompanied by gal pal Veronique Gaignard, an off-duty flight attendant and budding opera singer.

Dubois’ extramarital love life was not part of the official report, but it’s not disputed that the captain got just one hour of sleep the night before getting into Flight 447’s cockpit.


The BEA didn't think it was appropriate to delve into the reasons why the captain left the cockpit flying into a line of storms and took a while to come back after the plane went out of control.

From ABC News:

Although it was never revealed what delayed Capt. Marc Dubois, two independent sources told ABC News that the 58-year-old veteran Air France pilot was traveling socially with an off-duty Air France flight attendant named Veronique Gaignard.

Jean-Paul Troadec, the director of BEA, the French authority conducting the investigation into the Flight 447 crash, told ABC News that Gaignard was not part of their investigation because the agency was "not interested" in the "private life of the pilot." Troadec added that he did not think Dubois's alleged relations with Gaignard aboard the plane would have played a role in the accident.