Category: Tips

You’ll remember the training – in an EFATO (engine failure after take-off): pick a field ahead and never turn back. There are 5 compelling reasons for this
1. considerable height is lost in the turnback
2. there is the risk of stalling / spinning if you get too slow
3. you’ll be landing with a tailwind
4. in most case, a 180^o turn does not position you in line with the runway. A further 90^o turn is required, followed by a turn reversal
5. After all this, in all but the lightest winds and the largest airfields, you will have drifted downwind, leaving little runway left for the landing.

On my bi-annual last month in the Sportcruiser, we measured the height loss in a 180^o turnback. Starting above 2000ft, from a full power Vy climb, we cut the power to idle, simultaneously pitching down for best glide speed and initiating and completing a 180^o turn. We did this with take-off flap and flapless. We tested each at bank angles of 15^o, 30^o and 45^o (with a 5 knot speed increase to compensate for the increased load factor).

With flap, the best result was a 30^o bank turn which lost 200 ft. Flapless, the 15^o turn lost least height (200 ft). All other configurations lost 300 to 350 feet. These results can probably be explained by 3 factors: the extra drag of flaps, the duration of the turn, and the increased load factor (and therefore drag) in steeper turns.

In a real engine failure, the height loss will be more – due to the ‘startle effect’ and inaccurate flying speed in the heat of the moment. Furthermore, if we fly on QNH, we are not as high above ground as a quick glance at the altimeter suggests. Also remember that other aircraft may perform less well: the Sportcruiser has a better glide ratio than many trainers.

To reiterate: turning back is not recommended if you are below circuit height. If you wish to see for yourself, only do so at a safe height, with an instructor on board.

The wintry weather caused by the Beast from the East has resulted in some unfamiliar codes in weather reports.

The METAR for Birmingham includes the word SNOCLO – meaning the runway is closed due to snow.

The METAR for East Midlands includes a string R09/6503// which is a SNOWTAM. It decodes as “on Runway 09, deposit type 6 = slush exists, 5 = 25-50% of the runway is covered; 03 = 3 mm deep; // braking action has not been determined”. If you were flying regularly in these conditions, you would probably download a SNOWTAM decoder app’s.

As always the temperature and dew point are given, in this case M02/M05. Even at sub-zero temperatures there is some water vapour in the air. When the air is cooled to -5 degrees it will form a solid phase, snow! Sometimes a negative dew-point is called the snow or frost point. Even in sub-zero temperatures, it is possible for the air to be unstable and for CB’s to form, although they will generally be less dramatic as the total amount of water vapour held in the air is less.

The TAF for Lakenheath includes the string of letters TXM00/0120Z TNM04/0204Z. This is normally omitted in temperate climates but you’ll often see it in Scandinavia and Russia. TX = max temperature (0 degrees on the 1st at 2000Z), and TN = min temperature (-4 degrees on the 2nd at 0400Z).

Well not 101, but perhaps a few more than you think.

Starting with the obvious….
• Squawk code + Altitude reporting. On older transponders this was called mods A and C. On a modern transponder, they will be labelled ON and ALT. Always select ALT.
• Emergency codes. We may not expect to use the 7500 hijack code in our little GA aircraft, but 7700 (emergency) and 7600 (radio failure) may be handy. Don’t be shy of using them in those circumstances. They get immediate ATC attention, and pinpoint your aircraft location better than a vague “west of Abberton” which in the heat of the moment may not be entirely accurate.
• Listening squawks. You know the deal (I hope). Each listening squawk goes with a frequency which you monitor – no need to speak. It allows a controller to contact you if they think you are likely to infringe, before the situation becomes serious. And it’s not just “big bad brother watching you”. On one flight home, I was called up “G-EMSA are you on frequency”, “Affirm”, and offered a shortcut through the Stansted zone. Very helpful.
• 7010. This is NOT a generic circuit squawk. It should only be used at airfields that instruct you to use it – they will have an agreement to that effect with ATC. So Audley End, Andrewsfield and North Weald all use it because of their proximity to Stansted.

And a few less obvious….
• Flight timer. Most modern transponders start recording flight time immediately upon take-off. You can use this to record times at waypoints in your PLOG, or to back0caluclate take-off time if you forget to note it down.
• Up/down timers. A digital stopwatch is just a few button pushes away. Handy for detours and for timing instrument approaches, holds and the like. The transponder is more or less in eye-line, unlike a stopwatch on a kneeboard which requires you to look down.
• Lost 0030. If you are lost (or euphemistically “temporarily uncertain of position”), then 0030 is the code to use. It requires you to speak to someone, but also alerts ATC of someone needing help or who might infringe. Who might you talk to – the relevant Radar unit or LARS controller, but failing that D&D (Distress and Diversion, not Dungeons and Dragons) on 121.5 is a good bet.

I asked a range of pilots, including experienced instructors, how large they thought the ASI error would be. Invariably, they didn’t really know but guessed at “Ooh, maybe 10 knots, 20 knots?”. The answer is…… the ASI will actually read 140 kt, close to Vne. In other words it over-reads by 75kt! I was in good VMC but you can imagine how things could go badly wrong in IMC, relying solely on the ASI with no visual references.

To convince myself and my sceptical listeners, I ran the maths on a spreadsheet. Using data for the International Standard Atmosphere and carefully converting all units to the SI system, the speed error which I observed proved to be correct. If you want to know more, take a look at http://www.luizmonteiro.com/Learning_Pitot_Sim.aspx which provides an elaborate explanation and a simulator programme to try out the effects.

So we all know PUDSOD. If the pitot blocks with a dead fly, it over reads in a climb. But by how much? Suppose you climb 500 ft at 65 kt. What is the ASI reading at the end of that short climb? Answer next week!