Coaching Corner… Threats and Errors – how do we manage them?

Head of Coaching David Cockburn follows up on his earlier article about Threat and Error Management (TEM), with some thoughts on its practical application

In the May issue, I wrote a piece on TEM. This prompted some discussion, and the suggestion that I should describe its practical application, partly for the benefit of our Coaches. So here goes!

Recently I have been helping a pilot become familiar with operating his single-engine aeroplane from a strip in the hills. Although working from such a field was not new to me, having to teach someone else required a much more detailed consideration of threats and errors. I had to consider not only those which I was used to encountering, but also those which might appear when someone else was flying the aircraft. What’s more, I would have to try to teach what I was considering.

The strip was close to the brow of a hill, aligned mainly uphill/downhill with a gradient of about 2%, with a hedge at one end and an unobstructed progressively steepening downslope into a valley at the other. For simplicity let’s say it lay east-west with the hedge at the western end. To the south of the strip the ground was relatively level, while beyond the north edge of the strip it sloped quite steeply downwards. A major airport lay to the east, surrounded by its control zone, and the altitude of the base of its control Area and airways varied over a considerable distance around the strip.

We could list many potential threats from just these facts, but considering them all would take a lot of time. For example, different wind directions and strengths would present different threats. What I had to do was think, and encourage the pilot to think, about what particular problems we might encounter in the conditions which we were faced with on each take-off and landing. There was no point in worrying about what might go wrong on a different day.

Of course, the weather wasn’t the only consideration when considering potential threats. The aircraft performance was not ideal for the strip. While it could easily take-off and land on a flat, hard runway in the distance available in nil wind, the length and condition of the grass would affect the actual take-off distance, as would the slope and the softness of the surface. The size of the fin area would affect control on the ground, and the response of the flying controls at different speeds would affect controllability in crosswinds, and also in turbulence once airborne.

As one might expect, we needed to consider the threat that the engine would fail to produce its expected power. However, even the shape of the ground presented a possible threat. Pilots are taught to select attitudes and maintain them to obtain the performance they expect from their aeroplane. Surrounding hills presented a fluctuating horizon, so attitude judgement was made more difficult. And so, having considered threats, the potential errors needed to be taken into account. Human factors training suggests that even an experienced trainee’s capacity for learning is limited, and that misunderstandings will occur, so the instructor always has to be ready for the pilot to do something inappropriate at the least convenient time. That inconvenient time, and the most inappropriate action, would vary with the conditions in force.

As an example of the TEM considerations required, let us imagine a day when an active trough has recently passed the strip. The surface wind is 315/12kt gusting 18.

There is no point in taking off if we are unable to land, so it is logical to always consider the landing first, and that includes returning home if we plan to land away. On this occasion the forecast suggests a landing uphill. The crosswind would be close to the aircraft’s capabilities, but manageable for ground handling, take-off and landing, so if we use the correct techniques it should be safe to fly, although gusts and turbulence are likely, as the wind curls over the top of the slope. An increase in approach speed would be advisable, and the slope will avoid any problems with stopping after touchdown. However, there is always the threat that the forecast is wrong, or something blocks the runway, so we need to identify an alternate landing field with a runway more suited to the wind. We also need to know how to get there and carry enough fuel to reach it.

Our example flight involves general handling in the local area, which reduces the number of likely threats. It is always a good idea to operate upwind of the intended landing area, because we should be between any approaching bad weather and our destination, although we must consider the possibility of a CuNim developing behind us. That direction in this case takes us away from the CTR and the lowest of the bases of the controlled airspace, so if we stay below the lowest of the varying bases to the west we should avoid infringing it.

The wind favours taking off towards the hedge, but the recent showers have encouraged the grass to grow, and softened the surface. The aircraft handbook contains no performance details, so we have to rely on previous experience to determine whether the take-off and landing distances available are sufficient.

That previous experience is important, but must be appropriate. If we, or a previous pilot, have measured the distance the aeroplane used to reach a safe height (50ft) in similar conditions, that can be used as a basis which we can relate to in future. However, if these figures were obtained with only one person on board, we should remember, for example, that the CAA’s SafetySense leaflet 7 tells us that another occupant adds 20% to the take-off distance and 10% to the landing distance required. Once airborne, possible turbulence might suggest we should add five knots to our best climbing speed when close to the ground, so we don’t want to cut it fine.

Whether the distance seems adequate or not, we should always have a ‘stop point’ nominated for every take-off.

There is more than one way of deciding on that stop point, but if the aircraft hasn’t reached 2/3 of its lift-off speed before passing a ground feature about 1/3 of the way along the available distance, I suggest the take-off should be abandoned. That stop point is unlikely to vary with the conditions, so can be selected in advance for each runway, ideally by walking the strip (which will also help identify soft ground or molehills), and perhaps marking it obviously. If the lift-off IAS is 45kt, we need 30kt by the stop point.

If we find it impossible to take-off uphill, what if we were to take-off in the opposite direction? SafetySense leaflet 7 tells us that a 2% up slope increases our take-off distance by 10%. The tailwind component on the other runway will also increase the distance required, possibly by 40%, but in this case there is no hedge, and beyond the strip end the surface is smooth. The downslope should allow us to accelerate to a safe climbing speed, again considering the turbulence, once we have lifted off.

Engine failure threat…

However, we have to remember that getting off the ground safely is only part of the requirement. The threat of an engine failure is ever present. An into-wind take-off should allow a forced landing ahead at a ground speed, which should make even a crash survivable. If we take-off downwind, a forced landing ahead is unlikely to be survivable. Remember that road safety advert: “Hit me at 30 and I live, hit me at 40 and I die”? If we abandon a downwind downhill take-off it will also be difficult to control our direction and require a lot of ground to stop.

However, as it happens the slope at the end of the strip is steeper than the aircraft’s glide angle. It also curves gently left through about 120°, opening out into a valley with fields, which allow an almost into-wind landing in the event of a failure. A downwind take-off is therefore a possibility. Whichever we decide, the pre-take-off ‘eventualities’ briefing that we give ourselves ought to consider the situation at the time. For example, for an into-wind take-off it may go like this: “If anything unusual happens during the take-off run, or if we haven’t reached 30kt before we pass that tall tree (previously calculated stop point), I shall close the throttle and apply the brakes to stop. If we’re airborne and the engine isn’t giving enough power, I shall lower the nose, achieve 60kt (approach speed) and land on what’s left of the strip or aim for a clear area ahead or slightly right (towards the wind).”

Some pilots might like to add things to this brief like trying to restart, or switching off the magnetos and the fuel and calling ‘Mayday’, but I don’t at this stage. I believe we should concentrate on handling, because hopefully that will not only mitigate the failure risk, but also manage the possible fatal error of losing control, while concentrating on matters of less immediate importance.

So the threats have been considered and we have decided how we can mitigate the risks (although there’s always something we miss). Before we commit ourselves to action, however, we need to consider other possible errors.

Is the pilot competent (and current) in crosswind take-offs and landings? If not, as the instructor, I ought to brief carefully beforehand, and keep my hands and feet close to the controls ready to take over. If the pilot is inexperienced or conditions are really awkward, perhaps I should demonstrate rather than let him struggle. (If I don’t think I can fly a good demonstration we shouldn’t be flying!)

Remembering the difficulty in selecting appropriate attitudes, I shall have to emphasise the need to maintain the correct airspeed, and the need to select what appears to be an apparently stupidly low nose attitude once airborne, while the aircraft accelerates to climb speed. That will be particularly important if we take-off downhill, because not only will the air be sinking, but the pilot will be tempted to raise the nose at a familiar ground speed which will be higher than his airspeed.

The downhill take-off, and the wind, would take us closer to the control zone, so after take-off we should need to turn away from it early. However, we could also mitigate the risk of an infringement by obtaining a clearance before take-off, by telephone if we are below the radio line-of-sight.

We have planned our operating altitude to be below the airspace base. However, human factors tell us that during a training flight the crew can become distracted by the training, and altitude maintenance may suffer. We may even have taken off with an incorrect QNH, so can we alleviate this possible error? If our aircraft, or a personal device, has an electronic altitude warning system (preferably audible), we could set that before take-off to a suitable level, but otherwise set up and maintain radio contact with ATC, telling them what we want to do. At any rate, a transponder with altitude readout (Mode C or Mode S) would reduce the hazard we would present to other aircraft, if we entered controlled airspace without clearance.

I’m sure I’ve missed quite a few obvious threats and errors, so if you spot something I missed, pass them on via the Editor and your thoughts on how to manage them. No prizes, but keen to open discussion! ■