Transition Altitude for Oceanic Airspace?

[VPI Greenwood]

Does anyone know the transition altitude for Oceanic Airspace?

The base of most controlled oceanic airspace in the North Atlantic is obviously Flight Level 055, implying a transition altitude well below the North American 18,000'! However I have never seen it written in any of the flight planning publications.

[Pointer]

Do you wqant to get that low over an ocean???? <img src="eek.gif" border="0"> <img src="eek.gif" border="0"> :)

[Eric T Cartman]

5500ft in UK section - dunno about the rest !

[VPI Greenwood]

Pointer:
It's in connection with (military) maritime patrol flights where one often operates below FL055 without need of a clearance.

Eric T:
Is the UK 5500' written down anywhere? The problem, I guess, with 5500' would be the need to cross check with 1013/29.92 before reaching 5500' to see if one had reached FL055! (and thus remain below controlled airspace, if that was the aim!)

[Eric T Cartman]

VPI - I've not seen it written in UK AIP , but I got info from a senior ATCO @ Shanwick. FL55 is never allocated to prevent conflict with aircraft at the base using QNH (Nimrods perhaps ?)

[VPI Greenwood]

Thanks a lot - Senior chap at Shanwick good enough for me!