Flying IFR in IMC with a Single Engine Piston

[manucordier]

Hi,

Could you please tell me a bit about your experience while flying IFR in IMC with a light Single Engine Piston. I'd like to make a private IFR flight with 2 friends, in Europe, of about 500 Nm, possibly in IMC.

Here come my questions :

- Do you take a VFR map along just in case your VOR/ADF/DME or glasscockpit fails ? Or you trust your IFR certified airplane and just take an IFR map with you ?

- I had an instructor who imposed the following minima for single engine piston IFR flight in his school :

* Minimum Visibility for take off = minimum Vis for Landing x 1,5 (and no inferior to 1500meters)

* Minimum Ceiling for take off = minimum ceiling for landing x 2 (and no lower than 500 feet).

What would you do for a private IFR flight ? Do you find it too conservative ? Or not safe enough ?

Thanks a lot for your feedback.

Regards.

[what next]

Hello!

- Do you take a VFR map along just in case your VOR/ADF/DME or glasscockpit fails ? Or you trust your IFR certified airplane and just take an IFR map with you ?

The latter. Anyway, one is always in contact with an ATC unit (and I always take a handheld transceiver with me) who can provide you with vectors. I only have a VFR chart when I fly to VFR only airfields (also with Y and Z flightplans of course).

I had an instructor who imposed the following minima for single engine piston IFR flight in his school : ...

The school where I instruct IFR has very similar minima, which I observe when instructing. When flying privately, I'm happy with the legal CAT I minima (550m/200ft).
BUT I strictly refuse to fly SEP IFR with a cloudbase of less than 1000ft anywhere along the way. I have had three engine failures so far (luckily all in twins) and the next one is waiting to happen. 1000ft of cloudbase give you at least some chance to perform a survivable forced landing. And I do not fly SE at night any more.

[mad_jock]

you would be better in the Private flying forum. Some of the pilots down there do that sort of trip quite often.


Wannbie commercials in general will never fly a serious IFR route from A to B. Until they get a job.

And if your a wannabie commercial more power to you sir for doing it.

[proudprivate]

IFR in IMC in a single engine

- Do you take a VFR map along just in case your VOR/ADF/DME or glasscockpit fails ? Or you trust your IFR certified airplane and just take an IFR map with you ?

I always take a VFR map with me, but not in case of instrument failure, but in case I have to fly lower for weather (icing) reasons.

- I had an instructor who imposed the following minima for single engine piston IFR flight in his school : [...]

Upon passing my IR checkride, my examiner advised me not to take off with less than 1 mile visibility, which is similar to your instructor's advice.
Regarding ceiling, that would translate to your own minimums. If you are fine with doing an ILS to 200 ft under actual conditions, then the ceiling limit would be 200ft. In any case, the ceiling should not be below your own personal minimums in the approach to be flown.

Since then, I have taken off with airport minimums on RVR and no ceiling. I guess it depends on what kind of IMC we are talking about. If it is just a thin layer of fog and cavu 500 ft above that and airfields in VMC nearby then that is certainly defendable, even knowing that you cannot land back at the airport of departure.

If that is ok for you, then you should inform your passenger(s). If they are also ok with it, and you have a reasonable amount of actual IMC experience, then one could argue to go for it. The chance of an EFATO after a proper preflight and run up in a properly maintained aircraft are virtually nil. But all parties should be aware that, should an EFATO occur in these circumstances, chances of coming out unscathed will be slim.

[manucordier]

Interesting guys/girls. Thanks.

In fact, I don't feel comfortable to take off with a single engine and a ceiling lower than 1000 feet AGL. I think I will stick to that 1000 feet minimum minimorum ceiling for take off.

Thanks.

BTW, any other opinion, advice or if you wan to share your own experience, it is more than welcome.

Cheers,
E.

[peterh337]

- Do you take a VFR map along just in case your VOR/ADF/DME or glasscockpit fails ? Or you trust your IFR certified airplane and just take an IFR map with you ?

Yes. Running as a GPS moving map, too. You must have a battery powered backup for NAV & COMMS for a total electrical failure, which is possible even in many twins.

- I had an instructor who imposed the following minima for single engine piston IFR flight in his school :

* Minimum Visibility for take off = minimum Vis for Landing x 1,5 (and no inferior to 1500meters)

* Minimum Ceiling for take off = minimum ceiling for landing x 2 (and no lower than 500 feet).

What would you do for a private IFR flight ? Do you find it too conservative ? Or not safe enough ?

It is perhaps a very safe guideline but is not based on any legal requirements and is pretty impractical unless you are flying old wreckage.

It also depends on the actual figures. If your airport has an ILS with a 200ft DH then a min 400ft cloudbase is reasonable for departures. Similarly if it has high intensity lighting and your plane has an autopilot which can fly an ILS then you can land with a vis of 550m (I think; 800m otherwise) and again a requirement of 1100m vis for a departure is not too bad; anything less means you can't be sure there isn't a fire truck or whatever parked at the far end of the runway especially if departing out of hours when there is nobody in the tower.

I wonder if he bans night flight too.

If you don't like it, get yourself your own plane It's the only solution.

Of course there is much more to this.... surface weather is only a part of the picture in IFR ops; any monkey can get airborne under a 400ft cloudbase but it is high altitude weather is what will normally bite you (structural icing, CBs, etc). 400ft cloudbase is probably heavy warm front weather with tops ~ FL250 and the potential icing band in that will be ~8000ft thick.

Note also that "cloudbase" is the base of any cloud, whereas "ceiling" is the base of BKN or OVC only. This works in your favour in the interpretation of these rules, but not if the FEW or SCT is sitting on the glideslope when you get there

Your name isn't Eric by any chance? Maybe not; he lives in Cologne

[manucordier]

Of course there is much more to this.... surface weather is only a part of the picture in IFR ops; any monkey can get airborne under a 400ft cloudbase but it is high altitude weather is what will normally bite you (structural icing, CBs, etc). 400ft cloudbase is probably heavy warm front weather with tops ~ FL250 and the potential icing band in that will be ~8000ft thick.

Indeed, I was thinking about that... Flying in IMC from November to Marsh might be quite difficult in France/Belgium/Switzerland because of icing. With the 0° isotherm at 0 feet AGL, you cannot fly in a stratus at 2000 feet AGL or you'll accumulate rime ice on your aircraft. So what about winter IFR flight in IMC in Europe, forget it ?

[peterh337]

No; you just need to be careful in the conditions you fly in (e.g. avoid frontal weather), or fly an appropriately equipped aircraft (e.g. deice and radar), or be brave

Actually, at Eurocontrol flight planning levels, you are likely to have freezing temps all year round, even in Spain sometimes.

I have some IFR trip writeups here. These illustrate a fairly careful planning strategy for a non de-iced aircraft without radar.

[Duchess_Driver]

Remember its not just the full engine failure in an SEP thats a problem - it's a partial power failure or some other emergency that requires a circle to return maintaining VMC that can cause issues with a low base/ceiling or reduced viz.

[S-Works]

When flying privately, I'm happy with the legal CAT I minima (550m/200ft).

I assume that is with a fully coupled auto pilot? SPA non coupled AP is 800m. (At least in the UK, I stand to be corrected elsewhere).

Otherwise I would agree, I fly IFR to system minima. My modifier is that I won't fly unless the Icing level is above the sector safety level as I am flying a non de-iced single.

However the reality is that you will rarely ever encounter those conditions in GA flying.

[proudprivate]

I have had three engine failures so far (luckily all in twins) and the next one is waiting to happen.

I take it you fly a DA-42 ?

No seriously, that is statistically rare (unless you have 10000+ hours). May I ask what caused each of the instances ? Were they related ?

[achimha]

What would you do for a private IFR flight ? Do you find it too conservative ? Or not safe enough ?

If you set yourself such conservative limits, you will most often end up not flying at all and the only benefit of your IR will be ATC guidance instead of circumnavigating airspaces. I found that in particular avoiding low enroute clouds (for the reason that you could not perform a forced landing) imposes a major limit. My strategy is altitude. In Central Europe, there are so many airports that you should always be able to find an ILS equipped airport in gliding distance, provided you have sufficient altitude. Just today I flew from Northern Germany to Southern Germany and at FL140 I felt very safe despite low clouds in most places.

Like Peter said, your goal has to be to quickly climb through clouds and reach VMC for the enroute segment. Neither in summer nor in winter you want to spend your time flying inside clouds. Even in winter with icing, if the cloud layer is not too thick, you can pass through without picking up any considerable ice.

[manucordier]

Hi Achimha,

FL 140, flying above the clouds then ?

Ok but you've got a pressurized airplane then ?

Because, supposedly, we shouldn't fly above 10.000 feet amsl without oxygen.
(However, I must admit that during my training we did fly on airways above FL100 without pressurization)

[peterh337]

However the reality is that you will rarely ever encounter those conditions in GA flying.

How does that work?

FL 140, flying above the clouds then ?

Ok but you've got a pressurized airplane then ?

Oxygen

No oxygen = no IFR (practically speaking) at Eurocontrol levels.

Oxygen is the key to GA IFR. You pick the wx so you can climb through the wx at the terminal areas without getting iced up etc (which indeed implies a certain level of caution) and then you fly VMC on top when enroute, and climb as necessary. ATC always allows a climb "due weather" (if they are ICAO Level 0 English and don't understand "due weather" try "due severe icing" ) and the only time you can't do that is if the tops exceed your aircraft performance. But without oxygen you are limited to really nice days. Of course many people disagree with this strategy and they fly through frontal weather anyway, but they also have better stories to tell than I have (well not all of them...)

[achimha]

FL 140, flying above the clouds then ?

Ok but you've got a pressurized airplane then ?

Yes, above the clouds but no pressurization. I have a built-in oxygen system which I use above FL100. In winter, you can normally fly on top at a much lower level than I did but I wanted to go straight over Frankfurt's airspace which requires at least FL140.

IFR in a SEP without oxygen is rather limiting. Most of the time, you can fly on top of weather but for this you need to have the option to go higher than FL120 which I consider to be the highest usable level without oxygen.

What I love about IFR on a gloomy overcast winter day is when you break through the clouds and you are in bright blue and sunshine emerging from a bed of clouds.

[S-Works]

How does that work?

OK, Peter, how many times have YOU been flying on total system minima days from take off to landing?

I can count the number of days I have been flying in those conditions on two hands and I have rather more hours than you do. Even in quite marginal days that are nowhere near system minima light GA is never around.

So the reality is that most light GA IR pilots will look at system minima weather and call it. There is rarely a private flying trip THAT important!!

[172_driver]

Flying SEP in IMC is a risk you have to sign up for. It's like flying at night, it's all fun and beautiful until the fan quits. Perfectly legal but I don't think anyone really wants to touch the "what if" contingencies. Yes I have done a fair share of it, the school I was teaching at adopted FAR minimums (so 200 ft ceiling).

Apart from the engine trouble scenario, some things that need consideration:

- Personal minima, whatever you are confident with. When I was instructing I felt no problems going to minimums. But now having been away from it for a while and using A/P most of the time in my job I am not sure I'd take an OBI equipped C172 on a day with weather right at minimums.

- Instrument failure. I think we all had to prove we were proficient in flying without AI and/or HDG indicator on our check rides. But it's one thing flying under the hood on a CAVOK simulating with post-it notes a failed AI. Another thing have it happen to you subtly in IMC. Fortunately, the only time I've had an AI fail was in VMC. But it can happen… A very real audio file is circulating on youtube with a C210 (I think) getting out of control in IMC after loosing vacuum pressure. The G1000 AHRS is not immune to failure either, have had it happen. That was because of poor installation. But if one maintenance shop can get it wrong, I am sure others can too.

- In precipitation water can enter the pitot-static system. The C172 is a little bit susceptible to this. Even though there is a drain system, I have had both the airspeed indicator and altimeter show erratic indications. A colleague of mine was cruising happily at MDA in IMC when the altimeter "gave" and dropped 200 ft… so he was actually flying 200 ft below MDA.

- Icing is a very real threat to any aircraft not equipped for it. Before I go on a given flight, I check what the minimum flight altitudes are for my route and possible diversion routes. I used to fly in a mountainous area, normally quite warm but during winter could have freezing levels down to 3000-4000 ft MSL. Because the area was mountainous the MEA:s for many routes were quite high. However there were also coastal routes with much lower MEA:s that you could choose instead. Even though they weren't the preferred routes the ATC system was very flexible and if there was a legitimate reason for your request they could always help you out. Notwithstanding what other people's thoughts/experiences are I would not think about climbing through a layer of possible icing in a low powered SEP. What if you don't get through? It's best to avoid it altogether, even if that means no flying today.

So.. you choose if you are ready to sign up for it

But always leave yourself a way out…

[soay]

Originally Posted by 172_driver

The G1000 AHRS is not immune to failure either, have had it happen.

Me too, only it was nothing to do with poor installation. It was an intermittent hardware failure that caused the AI to slowly tilt to a 15 degree angle of bank, with no error indication. Fortunately, this was in VMC.

[what next]

Hello!

Engine failures:

No seriously, that is statistically rare (unless you have 10000+ hours). May I ask what caused each of the instances ? Were they related ?

1st: Magneto failure in a Cessna 421 during initial climb that resulted in wrong timing and firing sequence of the cylinders. The resulting vibrations were so bad that it was impossible to read instruments until the misfiring engine had been pulled back to idle.

2nd: A valve rocker arm broke in a Seneca during climb above level 100 leaving the inlet valve stuck open. The engine continued to run on five cylinders, but the turbochrger output escaped through the open valve. Impossible to maintain altitude, managed to hold 6000ft on 1 1/2 engines on the way back.

3rd and worst: Upon rotation the turbocharger broke off the exhaust manifold in a Cessna 421. The over-rich mixture resulted in an immediate rich-cut of the engine and exhaust gasses consisting mainly of unburnt fuel to enter the engine nacelle. Lots of fire damage inside the engine nacelle, cables and hoses burnt. Luckily the weather (just) permitted a wide 180 degree turn back to the runway with (just) enough time for an airliner that had lined-up behind us to clear the runway for us.

[peterh337]

Captain Bosey, the resident pilot forum sky-god, you must be pushing 20,000 hours now I am really impressed, since in that flyer on the Ontrack website it says

He moved across to SEP aircraft in 2002

I am truly impressed.

What I love about IFR on a gloomy overcast winter day is when you break through the clouds and you are in bright blue and sunshine emerging from a bed of clouds.

Yeah....

But always leave yourself a way out…

I agree 100% but there are times when this is not actually possible, 100% of the time. I can think of departures and arrivals at certain airports, or flights above an overcast like this. Or any flight on a really dark night. All you can do is to minimise those times when you are exposed, and the stats seem to support this e.g. many GA planes cross the Alps but very few crash into them from enroute flight. The case of a departure with a cloudbase too low to return to the airport is another one, and I think most people take the risk on that. I do a lot of things which I would not do in somebody else's plane but e.g. I rarely fly at night because there is no escape route then.

Upon rotation the turbocharger broke off the exhaust manifold in a Cessna 421

I know this could in principle happen at any time, but doesn't it indicate probable crappy maintenance? Most exhaust system failures are not sudden; they are the end result of a gradual degradation, with gases initially escaping through various orifices, and often the maintenance company bodges it with cement, which is OK until the whole piece gets blown out. A good 50hr check will pick up a lot of stuff. Exhaust systems are very expensive ($5k-$20k) and most people run them until they fall apart.