Many years ago I promised a flight in a cessna to one of my workmates. Having already booked an aircraft, I received a telephone call from the flying club telling me that the aeroplane had lost oil in flight. Indeed it had. I saw the little Cessna 150 parked at the back of the hangar with a brown windscreen, a sort of dusty and fly-filled gunge across the plexiglass curve.

No matter. They promised me another airworthy machine that was more or less the same. I shouldn't have any problems. Yet when I arrived at the airfield I saw someone sat in it with perhaps only half an hour to go before my allotted time. As it turned out, the gentleman had tried to fly it but found the radio unserviceable. No matter. I went up to the tower and asked if I could fly non-radio. They agreed with some caution.

It wasn't just the radio. On taxiing out with my passenger aboard I found the brakes weren't balanced. That could make landings somewhat interesting. No matter. I figured I was up to the job and the runways were long enough to avoid the need for hard braking. So we took off. At an indicated four hundred feet I followed stabndard practice and raised flaps. Except... It didn't look like four hundred feet. Odd... The pressure setting is correct...

As flights go, it was trouble free. The sun was shining, the skies were clear, and we had a somewhat noisy hour flitting here and there across southern England. Time to descend for landing, I yelled at my passenger over the roar of the engine. Whether he understood I have no idea but I got a nod from him.

Throttle back. The world becomes a strangely quiet place in the cockpit of a light aeroplane with an engine running at idle. Slow the plane down with a slight backward pressure on the stick and aim for seventy knots. Trim the aeroplane to settle at that speed. Eighty knots registered. Trim back a bit. Eighty knots. Okay... Trim back a bit more... Eighty knots. Huh? Trim back just a little more.... Eighty knots.

By now the aeroplane was feeling unresponsive and adopting an uncomfortably nose-high attitdue. I don't care what the airspeed indicator says - this cessna is going to stall any moment now. Sure enough I heard the first, barely perceptible warble from the stall warner. Nose down, add throttle, stay flying. It seems my airspeed indicator had failed. Not a safe situation. If I flew too slow on approach, recovering from the stall was not going to be possible. I flew home and landed purely by feel. Phew.

The reason I mention this anecdote was that I heard about the report from investigators looking into the crash of a french airbus into the atlantic a few years back. It turns out the pilot had taken a legitimate rest break away from the cockpit, and while the co-pilot was flying, the airspeed indicator returned an 'erronous value' resulting in a stall. The airliner descended from cruise altitude in three and a half minutes to hit the sea tail-down.

Stalls, in which the airflow over the wing is either too slow or turbulent to generate lift, are one the first danger situations a pilot is taught to cope with. What a stupid and unnecessary tragedy. More to the point, why did the co-pilot of a trans-atlantic jet not recognise the symptoms of a stall condition and maneuver out of it?

More Safety Concerns

I see from recent news reports that car safety research is looking into automatic collision avoidance. That's already available on a one or two models available on the forecourt, taking the form of a sensor that brakes when a crash with an object in front is interpreted as a danger. So far it only works reliably at low speed.

The reporter approached a car in front and looked away to talk into the camera. Obligingly the system worked and halted his vehicle. He said "It means that even if you look away, the vehicle will still stop."

Now the thing is, at first glance this all seems very clever, but I remember a newspaper anecdote aabout a law passed in Italy concerning the dangerous driving of taxi drivers. Because there were so many shunts caused by taxi drivers braking too late or too closely, the government decided that all taxi's should be fitted with better brakes. So the result was exactly the same accident rate, because the taxi drivers braked even later and closer knowing how good their new brakes were.

And now we're going to have these collision detectors fitted as standard. Is that actually a good thing? It might avoid the odd accident, but when drivers begin to lose that sense of awareness and caution, not worrying about looking where they're going since they know a gizmo will protect them, will it really reduce accidents? Speed might be the popular culprit of death on the roads, but a lack of observation is far worse.