Someone on Youtube paired the audio transmissions to the ADS-B recording of speed and altitude, and played the result. Perfect example of a stall-spin accident. He actually has a stall on the left wing, then recovers that, and a second later, he stalls the right wing, and she rolls over and spins in. He gives a "SHIT!" the first stall (L/H wing), then another "Shit!" when the right wing stalls, and then a final "Shit!" as the aircraft rolls over and heads for the ground.
Like a lot of aircraft, Learjets are prohibited from intentional stalls by their crews, at ANY time. When I was being trained on a Cessna 150, my instructor and I spent an entire day doing stalls, learning what they felt like, how to handle them, and how to do recovery from the spin that follows a stall. But we did this all at 3500 feet altitude, and the Cessna 150 flies very slowly, so it was no problem. They just mush a little, and recover as soon as you put the nose back down. They are a training aircraft, and engineered to give very gentle responses when students screw up. (My flight instructor always said that Cessna 150's flew best when the student took his hands off the control yoke, and put his feet flat on the floor)
Learjets have angle-of-attack sensors, that set off warning alarms, lights, and finally a vibration and pusher system that gives you a hell of a shake when you get near a stall, and actually pushes the control yokes forward, to avoid a stall. Most Learjet pilots never actually do a real stall in the aircraft in the real world. They do them in simulators only. They DON'T do them when in-flight training.
I used to go on stall flights at our service center. (Nothing glamourous, just acting as portable ballast in the cabin.) The aircraft normally had between 200 and 600 lbs of lead ballast installed, to make sure the nose dropped after the stall, and the aircraft could be recovered. They also took one of us along, so that if by chance there was a problem getting the nose down, our job was to go forward and climb on top of the center pedestal in the cockpit, to add our weight to the forward pitching moment to help recover the aircraft from the stall.
I probably went on over 100 stall flights. Basically, if you did any work on the wing, such as changing a leading edge, you had to do a stall confirmation flight, and this had to be done by company test pilots.
There were actually small pieces of metal on the leading edge of the wing, which were called "Trip Strips". Their purpose was to insure that a stall that was entered in normal flight, would stall both wings at approximately the same time, so that recovery was possible.
These were installed per the directions of the engineers, set perhaps 1/16" above or below the very center of the leading edge curvature. We would glue them on with epoxy, fly the aircraft, and if the stall was OK per the pilots, then we would rivet them in place, and remove the tape or epoxy, and then they would do another flight to confirm that all was good. If the stall was bad, the trip strips would be moved a little to try and correct the problem, and the flight test repeated. Stalls were checked on 16 stalls in a series, checking gear up, gear down, different flap settings, and also checking that the stall computer was correctly adjusted for that specific aircraft, and would do the stall warnings and pusher applications at the correct time.
Sometimes, the customer pilots would go along on these flights, and the test pilots would give them a really good briefing on stalls and recoveries, and then after they had done the first series of stall tests, if the aircraft was not homicidal, they would have the customer pilot sit in the R/H crew seat, and let him experience stalls for himself. THAT WAS THE ONLY TIME LEARJET PILOTS WERE ALLOWED TO STALL THE AIRCRAFT. It could ONLY be done in the company of a company approved test pilot. It was ABSOLUTELY PROHIBITED for any flight crew to just do this on their own. (The ballasting for most-forward center of gravity was the crucial item that they did not want customers messing around with.)
Aircraft that have a "T" tail, like a Learjet, encounter a problem called "stall blanking" in which the stalling aircraft itself blocks airflow to the "T" tail, meaning the elevator controls become useless. You can pull and push them full travel, and get absolutely no response from the aircraft. If the center of gravity is not set well forward by ballast, then it is possible for the aircraft to just mush down in that stable attitude, until it hits the ground. There is no way out. The lead ballast ensures that the nose will drop, and that normal flight can be resumed. Several aircraft also had "Spin Chutes" attached, which were there to literally jerk the aircraft out of a spin condition, or make the aircraft go full nose down, so a stall could be recovered from. I only saw a few times they put a spin chute on an airplane, and they were normally only put on for flight testng when they added hard-points on the wings, for installing missiles, bombs, or target towing gear.
When a Learjet stalls, it rumbles and shakes, like being on a roller coaster just as you get to the top. Then the stall happens. It can stall straight, in which case drop about 1500 feet while you recover.
Or it can fall off on one wing, which was usual on the initial stall flights. Whether left or right, the aircraft would snap over and try to go into a spin.
In either case, it is like a 2000 to 6000 foot roller coaster ride. There were only a few of us who went on these flights, as you needed to be able to do all this and NOT get airsick.
We normally were at an altitude of between 10K feet to 12K feet at the initial stall point, so there was plenty of room to recover. IF it fell off on one wing, the test pilots would typically let it go to see just what was happening.
Stall-spins took from 3000 feet to 6000 feet to recover from. (Obviously, if you are at 1000 feet on final approach, it means you are going to die.)
The test pilots were familiar enough with Learjet stalls, to be able to catch them even as they were happening, and arrest the conduct of the aircraft.
But that was NOT the point of their testing. The point of their testing was to make sure the stall behavior was as good as it could possibly be, thus giving ordinary flight crews the maximum safety margin they could get to survive a stall event. Thus the multiple flights and careful adjustments. (Prior to a stall flight, we checked and adjusted all the flight control rigging to ZERO, so the aircraft would fly straight and level. (This was done after cable changes as well, and I am proud to say that we usually had a flight where the aircraft was "hands-off" on the first flight after a cable change, meaning it flew straight and level with the control corrections not needed.)
Great info. Thanks.
