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Lessons Learned / your most scary flight

I've had a more subtle radio "failure".

I started up, talked to A/G, then taxied, lined up and took-off still talking to A/G.

Then they didn't answer when I called leaving the circuit and changing frequency to LARS.

Then LARS didn't respond.

COM2 did work, luckily.

Afterwards I reckoned that the squelch on COM1 was so aggressive that I could only receive while still close to the A/G transmitter. Luckily, COM2 had a less aggressive squelch setting. Both radios were fine.

From now on I will at least turn the squelch to the hissy end of the scale before I assume that a radio has failed...

Booker EGTB, White Waltham EGLM

I do not use QFE either. It's a recipe for trouble in instrument approaches, as I discovered when I "crashed" on an approach into Biggin Hill on FSX, when I forgot to reset the altimeter. Biggin is about 600ft up so that mistake will kill you.

However if some ATC station (RAF ones tend to use QFE especially) gives me the QFE, I read it back, because one is supposed to, but I ignore it.

Administrator
Shoreham EGKA, United Kingdom

Mainly flying a taildragger fro cruise, we kind of don't have that towbar/prop issue. Sure would be inconvenient, though, to go flying with it. I, too, almost forgot it once on the MS894 Minerva. However, we had an other prop strike problem, a couple of years ago. The Minerva's prop was back fresh from overhaul, when me and my father ran the engine. We pulled the plane out of the hangar onto the grass, did the preflight, entered the cockpit and started the engine. While we let her run (first run after the annual) for a while, the janitor prepared for mowing the airport and moved all taxiway markings by 10 Meters, so he could drive along the high grass around those markings. However, when we started to taxi to the active, after about 2-3 Meters of taxiing, we heard the distinct noise of the prop hitting one of these markers, with its metal herrings attached to it. Never seen my father that angry in my life. The Prop had two thumb-big dents and was beyond repair (it's quite decorative in my living room, though). Not a single minute airborne and run less than an hour. Unfortunately, there wasn't any prop for exchange available, not even from Hoffmann itself. But he had a nice composite three blade prop fresh overhauled, which the insurance paid for. Made the Minerva a real whisperer on take off.

I was with her in Elz EDFY one time and took off from there with a couple of friends. Four people on board about 1/3 to 1/2 fuel. I did the mass and balance, and I even did a take off distance calculation for the take off upslope. Not much though, but I didn't want to take off with 14 kts wind from behind, especially with that 1,4% of Elz. And we did take off in the calculated distance. And we climbed out. But unfortunately, the ground kept climbing with us, so we didn't see the ground leaving us for longer, than I figured and for linger, than I was comfortable with. Being on the downwind side of the hill didn't help either. But landing again wasn't an option due to obstacles, so I just kept full RPM (usually, I reduce quite soon) and Vx. The people on the ground said it was low, but not dangerously low, so there is much subject to perception, but whenever I take off against rising terrain, I sure as hell calculate the climb, too. And safety factors on top of anything else have risen, too.

mh
Inside the sky.
EDXE, EDXF, Germany

...my default has always been to set to QFE. In view of the overwelming opinion on here I may well reconsider, thanks

I was also trained to use QFE in the circuit, or when descending into the circuit. One reason I only use QNH now is that in some of the places where QFE is given, it is read out from an A/G station or sometimes by another aircraft in the circuit. It is therefore unreliable in some cases, and could be out by two or three millibars, depending on the quality of the equipment used. Whereas a QNH given out by an enroute ATC service is likely to be more correct, and applied to the published airfield elevation, is a better indicator.

I do not use QFE either. It's a recipe for trouble in instrument approaches, ... However if some ATC station (RAF ones tend to use QFE especially) gives me the QFE, I read it back, because one is supposed to, but I ignore it.

Is that wise?

If you are flying an ILS down to 200 ft wouldn't you prefer a current airfield-specific pressure setting, (QNH or QFE), rather than a regional QNH designed for terrain clearance over a wider area, updated "fairly often"?

I know the regional QNH is theoretically safer, (theoretically you would go around higher than you had to), but why ignore the most relevant information?

Altimeter 2 can still remain set to QNH for Safety Altitude purposes.

VFR, in the circuit, I don't think it matters. Even at QFE airfields, I frequently use QNH for any partial circuit on departure and QFE on arrival, because that's what I am given. (Obviously adjusting for elevation).

Booker EGTB, White Waltham EGLM

I am sure opinions are going to be split on this one, but one key for safety is consistency.

And most airports in the UK don't use QFE.

And no airports outside the UK use QFE.

One problem occurs when going missed, with the QFE on the altimeter. The missed approach procedure is specified wholly in altitude, so you must reset the altimeter as soon as you go around.

Yet the missed approach is a very high workload phase. You flew the approach all the way to minima, which takes a lot of concentration (even if just monitoring the autopilot and any stepdown fix altitudes etc) and then you have to suddenly throw it all away and climb flat out away from there. Resetting the altimeter at that point is quite a fiddly procedure; easily forgotten too.

The whole QNH/QFE business also translates to the way one reads the plates. If you make a habit of working in QNH only, you always read the first number

and ignore the little one in the (brackets). It's a consistent procedure.

I don't think QNH, as given by an airport, is any less accurate than QFE. Both are produced barometrically. At little places, the man has an old altimeter on his desk which he sets to either the airfield elevation (for QNH) or to zero (for QFE).

Administrator
Shoreham EGKA, United Kingdom

I don't think QNH, as given by an airport, is any less accurate than QFE.

I will certainly concede that!

And I can see the sense in the rest that you wrote, it just still feels wrong to ignore the most relevant pressure setting, just when you care about it most.

I am still in IR training, so I will grill my FI next time out :-)

Perhaps the answer is to request QNH if given QFE? Those RAF controllers do seem to "do things by the book" though.

Booker EGTB, White Waltham EGLM

I don't think QNH, as given by an airport, is any less accurate than QFE. Both are produced barometrically

True, but my argument would be that an airport with an ATC service is using (hopefully) modern and calibrated equipment, whereas an A/G service is giving a QNH/QFE based on an - as you say old - altimeter on his desk which may well be 30+ years old and not particuarly well calibrated. If I am landing at an airfield without ATC, and I think I have a more reliable QNH from elsewhere, then I use that.

An example case is me landing back at Panshanger which is A/G. With 10 miles or so to run before landing, I dial up the Luton ATIS frequency (120.57) and get the QNH from that. Its close enough to Panshanger to be reliable. Of course that process might not work everywhere, but using another example further North, I'd rather take a QNH from nearby Norwich ATC, than the very helpful man (I should add) sitting in his mobile truck at Cromer.

I don't think QNH, as given by an airport, is any less accurate than QFE. Both are produced barometrically.

Actually, the QFE is produced barometrically and the QNH is calculated from the actual QFE. So, indeed, one isn't more accurate than the other, if you leave aside numerical inaccuracies with the 10th decimal or so. And you can't set up your altimeter that accurate anyway.

Formula is QNH = QFE * exp(Mgh/RT) where M is the molar mass of air g is gravitational
h is height (or elevation) in meters, R is the gas constant T is standard temperature in Kelvin

The QNH from the next major airport can be more accurate than the QFE/QNH derived from an old altimeter, though, because of regular calibrations of the barometric instruments (or lack thereof on small airports).

Setting up the altimeter prior takeoff, I always setup the elevation on the altimeter and compare the QNH value in my altimeter to that given by the tower or info. By that, I have checked the accuracy of my altimeter and can take measures, if necessary. That includes, of course, taking actual elevation figures, on sloped airports, for instance. But these elevations are given in the AIP.

cheers,

mh
Inside the sky.
EDXE, EDXF, Germany

The golden rule of tow-bars, as put to me by an old engineer (who had got sick of dealing with the aftermath of customers attempting to take off with their tow-bars attached) is that when the tow bar is attached to the aircraft, it must also be attached to your hand. Conversely, before you let go of the tow-bar, you must detach it from the aircraft.

WS, that sounds like very good advice...it has never happened to me but many times I leave the tow bar attached while I attend to the pre-flight....in future I will follow your "old engineer's" advice!

EGPD / OMDW / YPJT, United Kingdom
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