When to select standard pressure

[sunnydaze 4]

Hi All.

I frequently fly out of EGCC (Manchester) using the Listo SID.  The Listo  departure(s)  holds you at 5000 ft until reaching the waypoint "Listo".  The transition alt for EGCC is also 5000ft.

When would I be expected to set to standard pressure?  Should I wait until above 5000ft ...or at reaching 5000ft?  If there is a great difference in pressure, if I select standard at 5000, it could alter my altitude by a few hundred feet..  I have been doing this in the sim for many years, but never sure what is the correct procedure.

Thanks if you could clear this up for me.

[fppilot 4,336]

5,000 ft?  In the USA the altitude for that is for higher faster aircraft and is at 18,000. However it appears to vary around the world.  A simple Google search turns up this:

https://en.wikipedia.org/wiki/Flight_level

 

[sunnydaze 4]

Thank you for the reply fppilot.  Since no one else has replied, let's just simplify it.  You are on route from KESN to KBOS. The local pressure is  30.34.   After takeoff, ATC instruct you to climb and maintain 18000 ft. When you level off at 18000 ft, would you set standard pressure , which would then read 17600 ft, or would you wait until cleared above 18000 ft   Same thing descending into Boston, if ATC told you to descend and maintain 18000 ft  would you set local pressure then, or wait until you are cleared below 18000 ft?

Thanks for the response.

[fppilot 4,336]

"At or above 18,000" is the way it reads in various FAA publications.  When descending it is "when below 18,000".

[seasley 17]

My understanding is that flight levels are set using standard pressure (29.92 / 1013) and altitudes are set using local pressure.  ATC isn't supposed to assign you to a flight level that conflicts (comes with 1,000 feet) of the transition altitude.

So in your US example if ATC assigns you 18,000 ft, they mean 18,000 ft at local pressure.  If they assign you to Flight Level 180, you'd set standard pressure and 18,000 feet.  If you're  currently at1 12,000 feet and climbing, and the ATC clears you to 21,000 feet, you go ahead and change to standard pressure when you set 21,000 feet, even though you're below the transition altitude.  You don't have to wait until you cross 18,000 ft.

In your UK example, I would interpret 5,000 feet at 5,000 ft at local pressure. When ATC clears you to climb above 5,000 ft (say to flight level 010), you'd set standard pressure and dial in 10,000 ft.

In the real world, I don't think ATC procedures would assign one aircraft to the same altitude as a flight level. However, ATC in MSFS can do some pretty strange things.

I was trying to find some looking at some of the FAA docs - ENR 1.7ENR 1.7 Barometric Altimeter Errors and Setting Procedures (faa.gov) (which would apply to US only), it seems that the lowest allowed Flight Level (i.e. above transition altitude) must be at least 1,000 feet above the altitude reading using local air pressure.  There's a table (TBL ENR 1.7-1) that defines the lowest usable flight level based on local altimeter.  So at your example 30.34 (which is high pressure), the lowest flight level is 180.  But if the is a low pressure system at the airport and the pressure is 28.91, the lowest usable flight level would be FL 200 - ATC couldn't assign you to flight level 180.

[fppilot 4,336]

7 minutes ago, seasley said:

My understanding

My understanding of Sunnydaze's question was where to set to standard.  The FAA language clearly states "at or above 18,000", which is where, not when.  I do not recall an FAA written instruction that states "when".  There are members here of the ATC occupation.  Perhaps one of them may comment on the question of when.

[ryanbatc 12,770]

At 5000 ft.  I've never flown irl in Europe but as far as I know it's very common to have transition levels at 5000, 6000 etc.

[fppilot 4,336]

30 minutes ago, seasley said:

So in your US example if ATC assigns you 18,000 ft, they mean 18,000 ft at local pressure.  If they assign you to Flight Level 180, you'd set standard pressure and 18,000 feet.  If you're  currently at1 12,000 feet and climbing, and the ATC clears you to 21,000 feet, you go ahead and change to standard pressure when you set 21,000 feet, even though you're below the transition altitude.  You don't have to wait until you cross 18,000 ft.

 

1 minute ago, ryanbatc said:

At 5000 ft.  I've never flown irl in Europe but as far as I know it's very common to have transition levels at 5000, 6000 etc.

Ryan, is it the case that when at 12,000 and cleared by ATC to FL210 you go ahead then and set the altimeter to standard pressure?

[ryanbatc 12,770]

1 minute ago, fppilot said:

 

Ryan, is it the case that when at 12,000 and cleared by ATC to FL210 you go ahead then and set the altimeter to standard pressure?

In the US?  Once passing FL180.

[G550flyer 1,007]

I have seen it as low as 4000 in different parts of the world. But in the USA, it's 18000. Flight levels start at 18000. So if climb to or above 18000, you will set standard. If descending below 18000, you will set local. The controllers will give you a setting when they clear you below 18000. The exception will be when operating in a MOA. For example, when I would fly out of Edwards to do some things, it was VFR and local altimeter way up as long as you were in the area.

Rick

[G550flyer 1,007]

Here's an interesting occurrence on one of my flights. I was leading a four ship with each ship having 500ft separation below the aircraft they were following. As we  were climbing, a controller asked if I had time for a question and I said sure. He asked, if your formation was cleared to 18,000, what altimeter settings would you all set? I pondered for a sec because I had never been asked that or thought about it before. I then replied with the formation mindset, standard. In essence, the formation is just one big aircraft with the focus on lead. It wouldn't matter anyway because they would apply formation rules since we are in a ALTRV. So if the flight is cleared to 18000, they will only see lead's squawk and communicate with her/him. They wouldn't see or hear the other aircraft each stacked down 500ft progressively. They wouldn't have to worry about them until we ask separation clearance and terminate MARSA. 

[svallott 1]

for exemple in Geneva LSGG

[svallott 1]

In geneva lsgg, when you are under 7ooo feets your are in qnh after 7000 you are standart pressure 29.92

 

[sunnydaze 4]

Thanks guys. I've been using flight sim for many years, but it has always bothered me when flying out of Manchester on one of the Listo departures.  It holds you at 5000 ft until crossing Listo,  and the trans alt is also 5000, so I finally decided to ask this question. I have always stayed at local pressure until I am above 5000ft,, so will continue to do that.  Thank you ALL for the help.

All the best.                                                                                                                                                                                                            

 

 

[fppilot 4,336]

👌Thanks for confirming!