Saying to yourself, airport 300ft, I'm 800ft, I'm turning onto final at 500ft, I need to be at 300ft by one mile, call out 200ft, 100ft, etc, etc, you know what I mean. If you are too low you are going to realise pretty soon if you are deliberately calling out the altitude. Relying solely on visual aids simply doesn't always work, short of an approved approach lighting system. My 2 cents worth
Excellent reply. In another life, this scribe flew 737's into black hole approaches into atolls in the South Pacific and Micronesia. No ILS and no VASIS and one could just imagine what it must have felt like to pilots landing on an aircraft carrier at night.
At 500 feet above airport elevation the copilot would look down at his instruments and call out the airspeed reading, altitude and rate of descent. The reason for this was the stable approach criteria. We pinched the idea from Ansett in those days. But there was another reason.
Below 500 feet, both pilots are concentrating on the appearance of the runway because with no glide slope guidance it was all too easy to misjudge the approach angle - especially through a rain swept windcreen where optical illusions caused by looking through water gave erroneous visual indications.
While non-standard, my personal preference under serious black hole conditions, was an additional final call from the PNF at 200 feet, of airspeed, ground speed, height and rate of descent. Something like: "200 feet..Bug plus five...Ground speed 135... Sink 700.
The reason for this was human factors. At 200 feet both pilots will probably be heads up - being a visual approach. Of course the PF is watching his own flight instruments carefully as well as the runway perspective. It is all too easy, however, for the pilot to concentrate on the runway perspective, correcting for drift and still miss an increasing change of airspeed and sink rate. At the same time, it is odd's on that the PNF is watching the runway with increasing interest with only 15 seconds to the flare. He too may miss an unexpected speed or sink rate trend.
By having the PNF go heads down momentarily at 200 feet to actually read out the airspeed and sink rate, then if the PF hasn't done it, then at least someone has. If through misjudgement, the PF has closed the thrust levers to less power than desirable for the conditions, at 200ft, even with idle thrust, (perish the thought on a 737), there is enough room for an immediate go-around and spool up.
Rate of descent in a light single engine type is easily changed with power. The problem crops up at night if the pilot inadvertently raises the nose a few degrees to stretch the glide as it were, and fails to note a rapid speed bleed. Next second, a stall warning sounds taking the pilot unawares and it is likely he instinctively pulls back on the stick close to the deck to prevent landing short. All this applies to a dark night black hole illusion where no visual glide slope aids are available.
In my mind that is why a deliberate heads down check of flight instruments at 200 ft, is a useful final check under the circumstances described, and still leave time for a go-around. A single pilot operation can adapt.