Think I learnt about flying today...

[goatwhacker]

I had one of those "I learnt about flying from that" experiences this morning... Please note this is posted as a confession as honest as I can make it, with the intention of hopefully helping other pilots with my level of (in)experience avoid finding themselves in a similar position! I accept full responsibility for what happened... Background: I'm a 100hr PPL, just starting to feel 'comfortable' with the whole flying thing. This is, of course, dangerous...
Awoke to find a gorgeous CAVOK day, no wind at ground level. The aim was to go looking for a prominent landmark in the mountains about 20 minutes flying time from where I'm based. Appearances can be deceptive however. The area forecast said the wind at 2000' was a 20kt westerly. At 5000' it was 30kt. Alarm bells should have been ringing by now but no, I told myself it wouldn't be too bad. I think I saw the 'CAVOK' bit on the forecast, rejoiced and didn't look at much more in any detail. So I also missed the whopping great SIGMET for severe turbulence, didn't I!!!
We went flying. It went fine until we got to the foot of the mountains and a few bumps appeared. "She'll be right", I thought, and pressed on.
We got very very close to the goal when I made my only good decision on this flight - this was not becoming fun; time to get out of there. This was sadly followed by one of my poorer decisions: Rather than turning right and staying over relatively high ground, thus avoiding much of the weird stuff you get from wind near cliffs, I went LEFT. Which put me over a valley. And needing to pass over a ridge to get home. A few seconds later we copped a significant DROP and, as my pax were crawling down from the ceiling, I decided to climb as much as I could to get out of there. Full power, hold best rate of climb airspeed and look in horror at the VSI reading more than 1000fpm DOWN. OK, now I was getting very very worried, and that ridge was looking awfully close (we were well clear but it appeared closer than it was). Finally got the aircraft up to a relatively safe level, still a little bumpy until we cleared the ranges completely. Got back to the airfield and at least landed nicely, so got some brownie points back from the pax for that.
Not one of my better efforts all round. A few glaring errors:
1) Read the forecast PROPERLY!!! Wind can do funny things to aeroplanes.... wind over hills is NOT good! SIGMETs are there for a reason and I'm still at a loss to describe how I managed to miss something so vital (and obvious!).
2) Continuing on. Perhaps the biggest one, the 'press-on-itis' thing. I should have turned around well before I did. Even better, canned it on the basis of the forecast!
3) Turning out over the valley. Why I did that I'm also not sure.
4) Going in so close to terrain on a day with strong winds predicted. Of course it's going to be bumpy; I KNEW that. But went and did it anyway. I was at least 1000' clear of it at all times but it didn't feel like it sometimes!

And finally, bad mistake to take people who have not flown in a lightie into this sort of environment. I'm dirty at myself for that - especially given the people I had on board who are somewhat special to me.

I got away with it this time. The bag of luck is a little less full. I will learn from this one!!
Any comments welcome... what else vital did I miss???

GW

[MyData]

omigod

Full power, hold best rate of climb airspeed and look in horror at the VSI reading more than 1000fpm DOWN

Just reading that brought a knot to my stomach.

I try and learn at least something from every flight. I guess every now and then we learn a great deal from a flight.

[IO540]

What "mountains" were these? There are no mountains in the UK.

Nobody reads sigmets or airmets anyway so nothing unusual there.

But if wind flows over terrain then yes it can get bumpy. This is a good flyer on the subject:

http://www.caa.govt.nz/fulltext/Safe...n%20Flying.pdf

There isn't too much of a problem with -1000fpm VS because the air isn't going to flow into the ground, so when you have descended to a few hundred feet, the downdraught should stop.

[goatwhacker]

...that would be because I'm not in the UK...
The aircraft was within W+B limitations, the engine was developing full power and I'm buggered if I knew what to do after that!! apart from coax it back up.

when you have descended to a few hundred feet, the downdraught should stop.

Yeah it's just the 'descended to a few hundred feet' thing that worried me!! I was over a valley facing (if I went any lower) a pretty sheer cliff. OK maybe it's my inexperience talking here but it scared the bejeebus out of me.
But that's a great pamphlet, thanks mate. I'm now much much more aware of this sort of thing!!

[coodem]

I'll admit I did the same sort of thing the other day. Had to take my partner to the station around the corner from my local flying club @ 05:30, weather looked good, wind a little high, but at least no cross wind factor.

Did a pre flight, took off by the time I was at 500 feet I saw all the clouds nearing in, next minute I was in the middle of the whole lot. It was as if someone put the duvet over the aircraft. Could not even see the prop in front of me, I was around 1000ft AGL, Now I started to panic, never been in this situation, not even with an instructor.

Well it took me a few seconds to take control of the situation (felt like hours) Maintain safe altitude, keep the wings level and maintain airspeed.

I reached for the GPS in the rear, turned it on, as I was going to use any help I could get. Finally I got site of ground again, had the runway in site. I was so relieved. landed, got out, looked up at the sky and it was clear, just my luck. Thought about going up again, but thought I had enough "excitement for the day

Just to make it clear my only intentions for the flight were to do a few circuits, a few touch and goes, or there was no way I would have gone up. (My airfield does not do conventional circuits, due to noise abaitments)

I now know I need to get a minimum of an IMC, just to deal with these brief, but yet so long moments

[IO540]

I really really do not wish to make the sort of smartar*e comments which are so common on certain other pilot forums, but

Did a pre flight, took off by the time I was at 500 feet I saw all the clouds nearing in, next minute I was in the middle of the whole lot. It was as if someone put the duvet over the aircraft.

suggests that a big improvement in preflight (weather) planning is called for.

I reached for the GPS in the rear, turned it on

It should have been ON the whole time, checked for satellite reception before starting the taxi. Do you push start your car, and use the starter motor only when too tired or when parked uphill?

[coodem]

Do admit I only did a quick TAF, as no METAR available, closest was 20 mile away. Returned CAVOK and VIS 9999.

This was the case, apart from that unlucky cloud that seemed to follow me for what seemed ages. Probably making it sounds worse than it really was, but it certainly was one of my worst nightmares

I agree, GPS should have been turned on. It follows me everywhere, but as I was only planning to stay in the "circuit" I saw no point at the time.
BUT have since realised I was very wrong, Plan the unexpected, You never know next time I might have to divert for one reason or another.

[MyData]

IO540

There isn't too much of a problem with -1000fpm VS because the air isn't going to flow into the ground, so when you have descended to a few hundred feet, the downdraught should stop.

That stands to reason, and hopefully one day I won't have to remember this thread. But if you are in the scenario as posted I guess faith in where the airflow goes won't give you a great sense of satisfaction.

[Wycombe]

Coodem

From your profile and your description of the circuits, I could take a wild guess at your base airfield

If you are where I think you are, the local weather (esp. cloud) may often be very different to that at a big airport generating TAF's just down the road.

....but I guess you know that now

[Vortigon]

Originally Posted by IO540

What "mountains" were these? There are no mountains in the UK.

Actually there are over 100 mountains in the UK I take it you were joking about this To the original poster I would advise perhaps a review of your met thoery on terrain/wind effects always helps to keep your theory fresh in mind with a deeper understanding of the wind changes/time of day effects etc even if you had missed the full weather broadcast you'd of been able to have a good idea of what to expect from observing the time of day/terrain type/cloud coverage etc As a learning experience its one you would be far better learning from condition observation and theory rather that your experience but at least it has maybe gave you a wake up call to review your flight routine planning and preparation.

[IanSeager]

Originally Posted by IO540

There isn't too much of a problem with -1000fpm VS because the air isn't going to flow into the ground, so when you have descended to a few hundred feet, the downdraught should stop.

Quite a few aircraft have crashed in the mountains because of severe downdraughts. One in Switzerland a week or so ago.

Ian

[Confabulous]

Have to agree with Ian and others here, there's plenty of evidence to suggest that a downdraught can force you into the ground. A few airliner accidents too, which is the reason why windshear alerters were invented.

Besides, what if a microburst occurs near a mountain and you happen to fly over it? The burst won't stop, it'll just drive you into the mountain.

[tangovictor]

I thank " goatwhacker" & " coodem " for there honesty, if it wasn't for hearing of others " mistakes " learning could be, very costly indeed !

[gcolyer]

IO540

Why should his GPS have been switched on? It is not a pre-req to VFR or IFR flight, although i must admit it is nice to have.

[dublinpilot]

I think IO540's point is not that everyone must carry a gps and have it turned on.

It's more that if you carry a gps as an emergency aid, but wait until you are in an emergency to turn it on, it may already be too late.

A non IFR pilot who has inadvertently entered IMC doesn't need the distraction of having to reach into the back of the aircraft, search through their flight bag to find the gps, secure it to the dash, turn it and and program it with a flight plan. Way too much distraction.

Along with this is the fact that it will take a little time for it to acquire a fix, even longer because of the speed of the movement. Longer still if it hasn't been used for awhile. In the mean time the VFR pilot is likely to focus on the GPS trying to see if it has got a fix yet.

Much better to have it turned on, programed, and left aside if you don't what to use it. At least it's all ready to go if the emergency situation occurs.

There was a report some months ago of someone on the other place, failing to find their destination, and in failing light. They decided at that point to pull out their gps which they had made sure had fresh batteries. However it had been some months since they had last let the gps acquire a fix. This combined with the speed of movement of the a/c and possibly a poor view of the sky, meant that 20 minutes later the gps hadn't acquired a signal.

GPS are fantastic safety aids. But if you carry one for use in an emergency, it's far better to have it prepared before the emergency, rather than need to set it up when it happens.

dp

[IO540]

I don't see how a downdraught can force a plane into the ground.

In the cases referred to, I would bet that there were other factors. For example, somebody flying in a canyon which was too narrow to turn around in and/or had "bits" sticking out of the bottom, and then being forced down is going to put you in a situation which you cannot get out of (insufficient climb rate and/or insufficiently tight turn radius). From what I have read about deep canyon flying (called "mountain flying" by those that do it; to me, mountain flying means flying at least 2000ft above the peaks ), this sort of thing happens regularly, wind or no wind.

This topic cannot be adequately disposed of with one-line replies.

But a plain downdraught caused by air flowing down a mountain, with the plane flying over flat ground at the bottom of it, should not be able to force the plane into the ground. If it can, please explain the physics involved.

[tangovictor]

I think the original poster had answered this ! he had intended to fly circuits, surely no one would need gps to carry this out ?????

[Mercenary Pilot]

Large-Scale Vertical Waves (Mountain Waves)

Mountain waves occur on the lee side of topographical barriers and occur when the wind-flow is strong, 25 knots or more, and the flow is roughly perpendicular to the mountain range.The structure of the barrier and the strength of the wind determines the amplitude and the type of the wave. The characteristics of a typical moun-tainwave are shown in figure 3-3-9.


Figure 3-3-9 shows the cloud formations normally found with wave development and illustrates schematically the airflow in a similar situation. The illustration shows that the air flows fairly smoothly with a lifting component as it moves along the windward side of the mountain.The wind speed gradually increases, reaching a maximum near the summit. On passing the crest,the flow breaks down into a much more complicated pattern with downdrafts predominating. An indication of the possible intensities can begained from verified records of sustained downdrafts (and also updrafts) of at least 5,000 feet per minute with other reports showing drafts well in excess of this figure. Turbulence in varying degrees can be expected and is particularly severe in the lower levels; however, it can extend to the tropopause to a lesser degree. Proceeding downwind, some 5 to 10 miles from the summit,the airflow begins to ascend in a definite wave pat-tern.Additional waves, generally less intense thanthe primary wave, may form downwind (in some cases six or more have been reported). These are similar to the series of ripples that form downstream from a submerged rock in a swiftly flowing river. The distance between successive waves usually ranges from 2 to 10 miles, depending largely on the existing wind speed and the atmospheric stability. However, wave lengths up to 20 miles have been reported.It is important to know how to identify awave situation.



Figure 3-3-9.—Schematic diagram showing airflow and clouds in a mountain wave.

Pilots must be briefed on this condition so they can avoid the wave hazards.Characteristic cloud forms peculiar to wave action provide the best means of visual identification.The lenticular (lens shaped) clouds in the upper right of figure 3-3-9 are smooth in contour. These clouds may occur singly or in layers atheights usually above 20,000 feet, and may be quite ragged when the airflow at that level is turbulent. The roll cloud (also called rotor cloud) forms at a lower level, generally near the height of the mountain ridge, and can be seen extending across the center of the figure. The cap cloud,shown partially covering the mountain slope, must always be avoided in flight because of turbulence,concealed mountain peaks, and strong downdrafts on the lee side. The lenticulars, like the roll cloudsand cap clouds, are stationary, constantly forming on the windward side and dissipating on the lee side of the wave. The actual cloud forms can be a guide to the degree of turbulence. Smooth clouds generally show smoother airflow in or nearthem with light turbulence. Clouds appearing ragged or irregular indicate more turbulence.While clouds are generally present to forewarn the presence of wave activity, it is possible for wave action to take place when the air is too dry to form clouds. This makes the problem of identifying and forecasting more difficult.

[Chilli Monster]

Originally Posted by IO540

Did a pre flight, took off by the time I was at 500 feet I saw all the clouds nearing in, next minute I was in the middle of the whole lot. It was as if someone put the duvet over the aircraft.
suggests that a big improvement in preflight (weather) planning is called for.

Actually it doesn't. It means that, just occasionally (and it has happened to me) weather forecasters get it wrong.

I reached for the GPS in the rear, turned it on
It should have been ON the whole time, checked for satellite reception before starting the taxi. Do you push start your car, and use the starter motor only when too tired or when parked uphill?

Oh for F*CKS sake!

Some people like to fly without GPS, some people like to look out the window, some people like to use a map occasionally. Flying isn't JUST about switching on all the gadgets and following the lines. Sometimes it's just nice to get out there and play, getting away for the world about you and doing things which others would give their eye teeth for. Sometimes it's just about tipping your wing into a cloud, flying some simple aero's, imagining you're something, somebody or somewhere else.

There are times when the GPS comments get really tiresome Peter - give it a break PLEASE!

(And can I also suggest a gliding course where Mountain Wave activity is coupled with hills and mountains - you'll garner a whole new respect for flying in such areas close to the surface).

[Confabulous]

There are times when the GPS comments get really tiresome... give it a break PLEASE!

I've just realised Chilli is absolutely right. In a way it's ridiculous to set yourself up like an airliner - we're mostly PPLs for god's sake, let's have a bit of fun. You can read all the accident reports, articles and opinions you want, but our flying is supposed to be fun, in a challenging way. I can't see the day we'll have a computer showing you which way to roll in aerobatics, how much G to pull, how close you are to stall alpha etc... it's getting damned ridiculous. Most PPLs are VFR only. Map reading is a good skill to have. So is weather reading.

Ernest K Gann said 'Rule books are paper - they will not cushion a sudden meeting of stone and metal.' Neither will your portable GPS if you fly into cloud with no IMCR or IR. Neither will the METARs and TAFs - they get it wrong too. There's been plenty of case of electrical failure leading to death, simply because they relied too much on the gadgets.

GPS is great - but it takes a lot of skill out of flying, sometimes when it's needed most.