Lock-on Altitude?
Guest
Posts: n/a
Lock-on Altitude?
Several JAA exam questions have referred to the lock-on altitude and the optimum altitude. Questions such as:
Both the lock-on altitude and the optimum altitude increase during the cruise. Which is the best level to fly at?
(a)The optimum altitude
(b)The lock-on altitude
(c)Between the lock-on altitude
(d)Just below the optimum altitude
Optimum altitude I thought I understood but what is the lock-on altitude?
Both the lock-on altitude and the optimum altitude increase during the cruise. Which is the best level to fly at?
(a)The optimum altitude
(b)The lock-on altitude
(c)Between the lock-on altitude
(d)Just below the optimum altitude
Optimum altitude I thought I understood but what is the lock-on altitude?
Guest
Posts: n/a
The only thing I can possibly think they might be talking about is the MAX cruise altitude in the cruise page of most FMC's ???????? (I have never heard this term used) . Either way to quote Boeing 'Best fuel mileage for a given speed schedule is achieved at optimum altitude'.
Sorry I can't be of more help
Best rgds
Sorry I can't be of more help
Best rgds
Guest
Posts: n/a
Um, just guessing here Alex, but its not something to do with autopilot altitude hold mode is it?
As in the pressure datum which the autopilot will maintain or "lock-onto".
I know that on some ancient aircraft (eg BAe146) the altitude hold mode will allow the aircraft to climb 100-200 feet as aircraft speed increases due to idiosyncracies of the particular pitot/static system and the severe lack of a digital air data computer.
Just guessing though!
As in the pressure datum which the autopilot will maintain or "lock-onto".
I know that on some ancient aircraft (eg BAe146) the altitude hold mode will allow the aircraft to climb 100-200 feet as aircraft speed increases due to idiosyncracies of the particular pitot/static system and the severe lack of a digital air data computer.
Just guessing though!
Guest
Posts: n/a
Another angle.
I am thinking about the atmosphere being "higher" or "thicker" at the equator than it is at the poles.
Consider a flight from the north pole to the equator. If the aircraft maintains a given flight level during the cruise its actual distance above mean sea level will increase as the aircraft progesses towards the equator. FL350 at the north pole is a lot closer to mean sea level than is FL350 at the euqator.
In this sense, although the aircraft autopilot may be "locked-on" to the pressure datum equivalent to FL350 its actual distance above mean sea level will increase.
Again, Alex, just guessing.
I am thinking about the atmosphere being "higher" or "thicker" at the equator than it is at the poles.
Consider a flight from the north pole to the equator. If the aircraft maintains a given flight level during the cruise its actual distance above mean sea level will increase as the aircraft progesses towards the equator. FL350 at the north pole is a lot closer to mean sea level than is FL350 at the euqator.
In this sense, although the aircraft autopilot may be "locked-on" to the pressure datum equivalent to FL350 its actual distance above mean sea level will increase.
Again, Alex, just guessing.
Guest
Posts: n/a
I think parachuters use the term "lock on altitude" for the altitude wher they pull the string. Obviously it doesn't have anything to do with this...
Just a question, referring to alternative (c): How can you fly "between the lock-on altitude?"
I don't think I've never flown between an altitude before.
Nick
------------------
"I have found that alcohol taken in sufficient quantity produces all the effects of drunkenness."
~ Oscar Wilde
Just a question, referring to alternative (c): How can you fly "between the lock-on altitude?"
I don't think I've never flown between an altitude before.
Nick
------------------
"I have found that alcohol taken in sufficient quantity produces all the effects of drunkenness."
~ Oscar Wilde
Guest
Posts: n/a
JT, no I did not mean to say that the autopilot altitude "wandered".
Rather that as aircraft indicated airspeed increases the altitude which the autopilot maintains whilst in altitude hold mode will increase by 100-200 feet, and then remain constant.
This is nothing to do with the pitch oscillation phugoids which are another feature of the 146, particularly in icing conditions.
As they say in Woodford, UK,
"Its not broken, its British!"
Rather that as aircraft indicated airspeed increases the altitude which the autopilot maintains whilst in altitude hold mode will increase by 100-200 feet, and then remain constant.
This is nothing to do with the pitch oscillation phugoids which are another feature of the 146, particularly in icing conditions.
As they say in Woodford, UK,
"Its not broken, its British!"