Originally Posted by
Checkboard
An aural low-energy “SPEED SPEED SPEED” alert, repeated every 5 s, warns the pilot that the aircraft’s energy level is going below a threshold under which he has to increase thrust, in order to regain a positive flight path angle through pitch control.
Thanks. As I suspected, it's not just speed but total energy. In this case, then, the proper warning should be "ENERGY." Or "POWER," which is the rate of change of energy; but as some have pointed out, that might be confused with the engine instruments. So my vote is for "ENERGY."
As most of us agree, the warning should point to the paramater in error. But despite your quote and others' elucidations, many still seem to point to the airspeed as the errant parameter, while from my understanding the speed can be perfectly normal and you can still get the warning.
Originally Posted by
_Phoenix
By definition Speed, speed, speed is a warning about the low state of energy, about decaying of the kinetic energy, which is 1/2*m*speed^2. The flight instructor would warn the student in the same way about dangerously low speed condition, thenafter the student realizes that he has to add more power or to relax the pitch up (in a tight turn for instance).
Not so. Speed is kinetic energy, not "energy." "Energy" is total energy, which is specifically what this warning references. For more detail, I'll just quote my own post from the high altitude stall thread.:
On a serious note, a big pet peeve of mine about this topic is when people call it a "high altitude, low energy" situation. It is not low energy, from 30,000 feet you have gobs of energy below you (namely, 1491 knots' worth) to use. That is, as long as you have the understanding and fortitude to use it.
Of course, I know they mean "low kinetic energy" and not "low total energy," but in that case they could have just said "low airspeed" with no loss of information. But no, they have to muddy the waters by using the fancy high tech sounding term. Unqualified "energy" is supposed to mean "total energy."