But srsly. In real life meteorology is a big deal for the military, and especially the air force. It would be mission critical information passed down as part of the briefing. I know for night time bombing in Vietnam, where knowing your location above the local terrain was of critical importance, updated pressure would be passed along by the airborne battlefield command and control center when passing along new missions.
It does have a radar altimeter. To get QFE I guess you just gotta fly low and make corrections to the barometric altimeter. I suppose it’s tricky to use the bombs in hilly terrain then.
The Viggen weapon system needs target altitude. Baro and radar altimeter measurements at your aircraft don’t give you target altitude, unless it’s at the same altitude as the ground under you, which isn’t going to happen all the time. You can think of this as a cheap alternative to having on-board terrain data like more modern aircraft.
Adjusting QFE for the target area isn’t terribly difficult. You have to have good altimeter setting first, which you can do at home base. Assuming the atmospheric pressure isn’t very different over the target, you can adjust your QFE by the delta between the altitude you last set and the target altitude, using the conversion factor of 1 millibar per 9 m (actually 8.68 m for you decimal place counters out there) of elevation difference. Note that this conversion factor will be different at altitudes much greater than sea level, due to the nonlinear atmospheric profile.
1013.25 millibar is the standard atmospheric pressure at sea level, but check with ATC to get the latest info.
DCS ATC does give QFE, but in inches mercury (e.g. 29.92). It’d be nice if the AI have you the units you need instead of having to convert. Alternatively, if you set your altimeter to 0 just before takeoff…voila, QFE, no matter what the crazy atmosphere is doing.
Now that I know the Viggen’s weakness, I’m going to endeavor so that never be the case.
What I always wanted to know: Do military aviators always use QFE?
I’ve heard the Russians do so. What about USAF? NATO? Swedish Flygvapnet?
QNH.
Italy uses QNH. I can assure you.
Pretty sure they use both, QFE is for local approach and QNH is the normalised altimeter settings used by all traffic.
Atleast, they should be, we are not a barbaric people still under the impression that digital watches are kinda neat!
Back at your home base, your ground crew silently hope you will get shot down so they don’t have to clean all those 16 bomb release mechanisms…
'Sactly! Digital watches are AWESOME!
Since we are at the movies…
Here’s a few clips from my gopro when I visited my old airbase. The museum has a really cool AJS 37 Simulator, made from a real cockpit, and the 36 sq.m. screen I mentioned earlier. This was a couple of years ago, and not all systems were functional in the sim. I flew open canopy to be able to talk to the instructor to my right. You can see his hands every now and then. I cropped the video to remove the canopy and instructor. That unfortunately means you don’t get to see the full screen view. I also threw some easy listening freeware music on to it, as the gopro didn’t pick up much of the sim sounds anyway.
If you need some coffe break entertainment:
Perhaps you’re confusing terms? QNE is standardized altimeter (29.92) for above 180 and QNH is the pressure adjusted setting used typically during the departure and arrival phases.
QFE isn’t really referenced as far as I’m aware. If you need your height above the field you use your RADALT or you do a little math from either already knowing the field elevation or, if not, looking it up on the approach plate.
I suppose I do, I’ll have to look it up in ze books but I can’t be bothered too much right now ;). I’ll go with what you say!
I had to look it up myself, it’s not like I’ve ever actually used terms like QNH outside of a discussion like this!
When I joined the RAF back in 1990 they were still using QFE, but dropped it for QNH shortly afterwards. Evidently because that was what most other countries were doing. I have only used QFE on one occasion, when flying to Murmansk a couple of years ago.
What about Navy or Marines? Also QNH?
How I remember it
QNE = pressure, no exceptions, no errors - the altimeter setting so that the altimeter reads zero at sea level on a perfect standard day, i.e. 29.92 inHg, 1013.25mb, 760mmHg, etc.
QNH = pressure, nautical height, or not here - the altimeter setting so that the altimeter reads zero at sea level for current atmospheric conditions.
QFE = pressure, field elevation - the altimeter setting so that the altimeter reads zero at some reference point (like an airfield).
As a civilian pilot in the US, we used exclusively QNH. In fact, I don’t remember ever referencing it as “QNH”, it was always just “altimeter setting”. It was also standard to ensure the altimeter was reading the correct field elevation just before takeoff, which ensured you had a good altimeter reading in case the atmosphere changed since you got your update (very rare for it to change much).
QFE is convenient in that you don’t have to memorize (and possibly remember wrong!) the airfield’s elevation since it’s always at zero for the right QFE. But you do lose the ability to speak altitude with folks around you. It’s like having a different altitude reference for every airport! In fact, that’s exactly what it is!
Russia uses qfe extensively, uk GA also uses qfe a lot at aerodromes (or used to back in my puddle jumper days). Qfe i find is quite handy
That’s how it has been taught to me as @EinsteinEP and @Bogusheadbox box say. I suppose it differs per country and regulatory authority.
USAF and us military anyhow pretty much exclusively uses QNH, can’t think of any civilian place I’ve flown that uses it either stateside. Brit fields almost exclusively use QFE, we always fly around QNH or with 2992 set, so if we drop into a British field for an approach they either hear our accent and give us QNH or they don’t care and give us QFE, it is also dependent on if there are aircraft operating in the pattern at that time since everybody needs to be on a similar altimeter setting. If you look up approach plates for British military airfields like conningsby or marham, the altitudes on the grandstand view will have two numbers, one for QNH, one for QFE. It’s a bit complicated but we keep it fairly straight
You heathen.