Archived

This topic is now archived and is closed to further replies.

Guest GBPilot

Flight Level and Crossing Restrictions

Recommended Posts

Hi EveryoneIn the UK barometeric pressure is unstable in winter months and lots of button B is required on a local flight to maintain correct flight levels with auto pilot. Recently on a flight from Heathrow to Manchester, RC after telling me to descend to 12000 ft which I do in good time, decides to give me four warnings that I have not reached 12000 ft and consequently tells me I have not met my crossing restriction and sends me on a long detour to the airport. No matter how many times I press button B after the first flight level warning, I cannot stop RC from giving me the other three warnings and detour etc. Anyone else had this problem? If so how did you solve it? Flying all of the tutorials was no problem!GBPilot. :(

Share this post


Link to post
Share on other sites
Help AVSIM continue to serve you!
Please donate today!

Ah, you're clearly not a regular reader of this forum. :( The 'B' key works only with the US system of a fixed Transition Altitude of 18000ft. Using it outside the US where the Transition Altitudes vary, will give - as you've just found out - incorrect results. When flying outside the US, do not use the 'B' key - set your altimeter manually. Going to your specific flight in the UK, your problem is caused by your incorrectly set altimeter. The UK has a Transition Altitude of 3000ft with variations at certain airports up to and including 6000ft so you would not have been cleared to 12000ft by the controller but to flight level 120 which would have required your altimeter to be set to 1013.2 mB - pressing the 'B' key would have set the QNH (the local pressure) which is incorrect and caused the controller to issue the warning.When you're operating at or below the Transition Altitude (6000ft in this case as you were inbound to Heathrow) you must have your altimeter set to QNH and your vertical position will be reported as an altitude. When you're operating above the TA, your altimeter should be set to 1013.2 and your vertical position will be referred to as a flight level. The RC controller will help you with this by preceding all vertical clearances at and below the TA with the word "altitude" and above the TA with the words "flight level". The co-pilot will also remind you to check you have the correct setting on your altimeter when climbing through the Transition Altitude or descending through the Transition Level by saying "altimeter check". Remember, clearance to an altitude = QNH set; clearance to a flight level = 1013.2 set and you won't get yelled at by the controller.I think it might benefit you to fly the European tutorial again, paying particular attention to the altimeter settings shown there.Pete

Share this post


Link to post
Share on other sites

Also you will find that you can re set the TA value in the FMC if you are flying an aircraft which is so equipped.IN the PMDG 737 this will affect the colouring of the pressure readout thus acting as another reminder.However as mentioned by Pete it doesn't affect the behaviour of the B key press.

Share this post


Link to post
Share on other sites

Thank you so much PeteP for your detailed answer. I've got to admit I didn't complete the European test flight. Great reply and thank you chrispeel for your reply also. I am now a Happy Little Bunny! :(

Share this post


Link to post
Share on other sites
I am now a Happy Little Bunny! :(
I'm delighted to hear that - enjoy your flying.Pete

Share this post


Link to post
Share on other sites