Ground Rush and Other Shocks
Chris Price, a glider examiner and tug pilot looks at failure to recover from stall/spin in winch launches and other fixed wing take offs, accidents in the circuit, approaches to land and field landing accidents. He identifies ground rush as an important factor in low level Loss of Control.
It is instructive to note that in most gliding cases catastrophic Stall/Spins are initiated at or below 500ft and I understand that the GASCo stall and spin investigation in 2010 showed that nearly all powered aeroplane fatalities occurred at circuit height or below. Many accident investigations indicate that the pilot apparently made no attempt to recover from a stall or spin or took inappropriate recovery actions.
The current thinking is as follows:
Cause of Stall/Spin accidents
… Fly the ‘plane.
My question is that while we all seem to accept that overload and/or distraction are usually present at the initiation of the stall, why do pilots so often fail to carry out a competent recovery as soon as the signs of Loss of Control become apparent? It does appear to me that the current advice to “fly the ‘plane” or in some cases, “retrain stall/ spin awareness and recovery techniques”, is not helping to reduce the number of accidents. So my point is that there must be another underlying reason why no recovery is made. A different type of training may be required.
My long held thoughts on appropriate training are that the pilot cannot recover from a low level stall/spin because:
1. he has not been trained to do so. He has not seen the low level stall/spin and practised recovery at that level at which incorrect recovery leads to a fatality.
2. he has not stayed in practice in that recovery technique
He cannot “fly the ‘plane” as currently advised and “retraining” as currently undertaken, will not help him. So current advice
needs improvement as I shall explain.
It is my opinion that to help the pilot “Fly the ‘plane”
1. He or she must be “trained differently” from day one.
2. He or she must stay well practised in the new technique.
Evidence that a new type of training is required which includes practising recovery in the low level stall/spin scenario comes from my own experience of many years instructing and examining reinforced by Dan Gryder’s experience. This was reported in GASCo Flight Safety magazine’s Winter 2016 issue. Dan related how, following the death of an experienced ex student and two passengers as a consequence of an engine failure at about 300 ft Dan subsequently discovered by creating surprise actual engine failures at low level and videoing the pilots’ reactions that their first response at this low height is often to pull back on the controls. Only by taking control was he able to avoid further disastrous LOC-I in these cases.
This evidence is reinforced by the summation – Human Factors Considerations below.
Pilots can be taught to recover from stalls and spins at heights above 2000ft and will usually be happy to demonstrate their entry and recovery to you when asked. On annual and currency check rides successful spin recoveries and wing drop stall recoveries are seen above 2000ft. Many pilots with an instructor on board will be confident to make these recoveries down to 1500ft, only a few are confident at 1000ft. Few gliders can be used safely to initiate a spin below 1000ft and therefore to investigate potential problems further, a stall with a wing drop can be safely initiated at 500ft. The scenario is ideal for the purpose of this investigation because in the mind of pilots under test, as far as they are aware, failure to take the correct recovery action will result in a fatal spin.
Below 500ft the inherent problems with current thinking on the cause and advice given to pilots soon become apparent: pilots fail to recover from wing drop stalls and current advice has no effect. Even the pilots who were confident and able to recover at 1000ft now make a rapid, full aileron movement to pick up the stalled wing and pull the stick fully back to raise the nose. The correct recovery technique, requiring pilots to move the stick centrally forward, which they have been practising at height only minutes before, completely eludes them. The cause of the inappropriate recovery actions I suspect, and this is the point of this exploration, is that the rapid rate of descent during the stall, gives rise to a phenomenon known as Ground Rush, a phenomenon never experienced before by the majority of pilots. We all know that nearer the ground, rates of descent are more obvious and this is particularly so below 500 ft.
In a glider, the increased but controlled rate of descent seen on an approach when the airbrakes are operated is what they are used to seeing. (In a power plane, full flap and throttle set to idle.) It is benign compared with the rate of descent seen when fully stalled. For a stall recovery, we now expect the pilot to move the stick forward to regain speed, increasing the apparent rate of descent further. In addition to the abnormal, high rate of descent, the pilot may have detected the start of the rotation which is to the uninitiated an alarming experience.
To the panic stricken pilot the “intuitive” reaction must be to pull back on the stick to climb away from the ground rushing up towards him. No recovery is made … As many as six training sorties have been required to overcome inappropriate use of the controls.
From the evidence above we must conclude;
1. that pilot training must involve recoveries from low level stalls/spins.
2. the pilot must stay in practice in those recovery techniques.
3. Late Field Selection by glider pilots must be outlawed (discouraged?) by competition rule changes and “serious re-training measures” before re-solo for the non-competition pilot. See the Box below for an illustration of just how risky this can be.
Particular considerations for gliding instructors
1. The training must be undertaken only by well trained, competent and confident instructors who are themselves well practised and current in low level recoveries.
2. The BGA is world renowned for the safe winch launching initiative which includes practising low level launch failure recoveries designed to prevent the stall/spin. It does require pilots to lower the nose, often from a climbing attitude to a recovery attitude, bringing the ground into view closer to the ground than they will be used to. Practising recoveries from a low level fully developed stall may be regarded as a progression or development of the launch failure training.
3. We must not repeat history and follow the powered flying world’s idea that stall/spin training should be abandoned because more accidents happened in training than when pilots were left to their own devices. In my humble opinion and as evidenced above, power flyers failed to address the root cause: they failed to train the instructors to safely carry out the task they were asked to perform.
Chris has been flying since 1977 and passed his instructors course in 1983. He is a Regional Examiner and has served as a Senior Regional Examiner. He is also an experienced power pilot with 2050 hours power flying including over 700 hours towing.
NOTE: Chris’s views do not necessarily represent those of either GASCo or the BGA. They are presented here to promote thought and discussion.