Looking for pointers/advice/ideas

[piperboy84]

Looking back over today’s flight and trying to think through what I could have been done better, if anything, and hoping someone with more experience may have some thoughts. The plan was to fly from the farm strip near Dundee on the east coast directly west to Oban on the west coast, both departure and destination are essentially at sea level and were reporting negligible wind, winds aloft at 3000 were forecast for 19MPH directly on the nose. The flight involved leaving the Strathmore valley and climbing over the southerly portion of the Grampian Mountains that top out at about 4000ft.
I set off and decided on an en-route attitude of 5000ft, light winds on takeoff and extremely smooth cruise climb to the beginning of the mountain range, my normal cruise airspeed at 2350rpm is 110MPH, the GPS was showing a ground speed of 75MPH which is more of a headwind than I had anticipated. I started experiencing light turbulence., I should point out I have done several trips over the high deserts and mountains ranges of the western USA and have experienced light + moderate turbulence, although I find it uncomfortable it does not overly concern me. A little further on just west of Aberfeldy over Loch Tay (which is about 100m MSL) in addition to now experiencing moderate turbulence I was getting pushed down at about 600fpm with full power and climb configuration I was finally able to arrest the decent at about 3600ft. I assume it was a “mountain wave” coming over the approximately 3900ft ridge at my 2 o’clock, this mountain was the first of the high ones on my route, I decided to do a 180 and head back to my home field picking up a ground speed of about 150MPH.
Upon landing I thought about my options and what I could have done to handle the situation better and came up with the following:
1. Went for a higher en-route altitude perhaps 7000 to 8000 ft which I assume would have kept me out of the “mountain wave” area on the lee side of the hill, although this may not have allowed me to avoid turbulence.
2. Went with the decent (i.e. not fought the push down) and descended to just above the loch where I assume the air would have been more stable with less or no turbulence and continued on my journey snaking along the lochs and valley floors at low level.
Anyone any thoughts?
(My aircraft is a 180HP Maule)

[stickandrudderman]

When approaching the mountain there should be no delay in turning downwind as soon as you experience the forced decsent. You certainly should NOT consider tolerating the uncontrolled descent in the hope that it might get better. Your options are diminishing with every passing second.
Selecting a higher MSA may have allowed you to continue, it may not. Your headwind component could have been even stronger higher up and rotors can extend quite some distance from the mountain anyway.
A decision to turn back and land safely is always the correct one, so well done for that.
I can recommend an instructor in Switzerland who will teach you everything you need to know about mountain flying and it will be the best thing you could possibly do in an aeroplane that doesn't have hosties!

[cats_five]

The best way to avoid mountain wave is to fly round the mountains, not higher. Gliders in Scotland (and other parts of the UK) regularly go up to FL120 and higher, so you can see the flaw in your plan. Additionally, the hills above Loch Tay are well known as a wave hot spot.

[Maoraigh1]

Flying through the valleys, you can stay with the updrafts. For instruction, try Aboyne or Feshie Gliding clubs - nearer than the Alps.

[abgd]

Or Highland Aviation at Inverness - mountain flying for powered aircraft.

[2high2fastagain]

Great advice. Same sort of thing happened to me once with a brisk southerly breeze at Brecon. Got the same symptoms. A few bumps to warn you and then the VSI needle unpleasantness. I turned back immediately. My take on it is that if you're not in command of the aircraft, which is effectively the case if the downdraft is pushing you down faster than you can climb, then simply go somewhere else where you can be the commander (obviously before you make a mess in someone's field).

[thing]

Looking at it from a glidery point of view SOP in sinking air is to get the nose down and get out of it ASAP. Counterintuitive I know but the best way to minimise height loss.

I would imagine (although I'm a new power guy and more than willing to be shot down on this one) that the best thing to do in wave in a fan driven a/c if you can't turn is to stick the nose down and head straight into it. Don't turn parallel whatever you do. This of course assumes that you have enough height......

[VP-F__]

as thing says don't turn parallel with the high ground that is producing the updraft unless you want to remain feeling at the least uncomfortable. Obviously what you did is the correct thing given how you felt at the time, I am not at all familiar with the geography of where you were and what was around you in terms of high ground downwind but if you wanted to continue there may have been a couple of options.
Given that you had a decent sink rate and turbulence would suggest that you were on the breaking side of the wave, if you had adjusted heading towards the high ground you may well have found the rising air on the upwind side of the rotor. You could then have adjusted track to parallel the high ground, throttled back and enjoyed surfing along the smooth part of the wave. The second option would have been turn away from the high ground and found the uplift further downwind as the wave came back up again.
As has been suggested already the best thing to do would be to go flying with someone who is experienced in reading the signs and knowing where to look and go for the safe routes.
Happy flying.

[gasax]

Pretty standard for the sort of route and conditions you were flying. You should expect the winds over the Grampians to be signifcantly stronger than forecast - apart from the mountaining forecast (sometimes!). Essentially the airflow goes over the top and is 'squeezed; and so accelerated. It also forms waves and they males constant altitude difficult.

If you want to fly at constant altitude you will need to change power and direction frequently. Each wave will give you lift and then sink, if you are flying obliquely to the wind both can last for a significant period.

I rarely ever fly at constant height in this area because of it - go with the height gains and accept the losses. Occasionally the losses can be pretty big - decide on whether the loss will take you down towards the rotor on the leeside of the high ground - if it looks like it will - change course and power early - under all circumstances do not get into the rotor area - with 20 knots very bad things can hapen there. Otherwise just enjoy it.

With a little practice you can optimise the life/sink ratio and get some free performance. I seem to remember some good basic information on the Transport Canada website on basic mountain flying.

[piperboy84]

Sorry to resurrect this thread, but as the OP I have come across a repeat of this situation and have been given instruction on how to handle it. I would like to see if others had an opinion on the matter. I am currently in Los Angeles building time in a similar make and model to my plane in Scotland Maule MX&7) for insurance requirements and a BFR (flight review). I retained the services of a respected CFI here, and today we flew from Long Beach (sea level) to Big Bear airport(appx.6300ft) during the flight over the mountain ridges we experience light chop and I talked about my experience of downdrafts in Scotland as detailed in my original post. The CFI suggested as a rules of thumb that when approaching mountain ridges where there are signs of rotors/downdrafts such as lenticular clouds and ever increasing turbulence, that for every 10 mph of wind coming over the ridge add 1000ft of altitude and cross it at a 45 degree angle. (essentially get to the altitude you need prior to getting near to crossing the ridge) Applying this during my Scottish flight where I experienced 30MPH + headwinds would have given me an altitude of appx. 7000ft crossing the 4000ft ridge as opposed to the 5000ft altitude I tried it at. Anyone any thoughts on if this theory would have prevented me from experiencing the worst of the turbulence and downdrafts?

[gasax]

For a single big ridge adding this sort of height will get you out of the turbulence. But the Grampians are the best wave soaring area in the UK, the UK height record was set there and is way over 20,000 ft - which gives you a pretty good marker on just how big a 'wave' can get.

On an average day if you see lenticular clouds in this area they typically start at 5000 and go on upwards. The turbulence on the leeside is usually not really apparent from above 50% of the height of the hills. So the advice from California pretty much 'fits'.

Crossing the ridgelines at 45 degrees is universal advice - but really only necessary if you're pushed for height or likely to encounter the leeside rotor.

The only real problem is that whilst you can usually get to these sort of heights on the east side of the Grampians the prevailing SW airflow often means the windward side has a lot of low cloud forming on it. So descending to a west coast destination will mean searching for a hole or going a fair bit further west to the coast.

[Captain Smithy]

I'd recommend "Mountain Flying" by Sparky Imeson. You can get it from Transair, it is an excellent book full of advice on crossing ridges, valley flying, dealing with mountain waves etc.

[cats_five]

Winds of 60 knots are well known to those of us who fly gliders in Scottish Wave. That's 70mph so you would have to cross at 7,000' above the ridges - say 12,000' amsl.

That's O2 country. Personally for Dundee - Oban I'd go round the mountains, not over them if flying power when there is good wave.

[mary meagher]

Piperboy, the best advice here is to visit Deeside Gliding Club website, and then book some flying - those folks know all about wave and how to use it.

It mentions, by the way, that the height record set there is 38,600 feet....

They offer instruction at quite reasonable rates. In gliders fitted with Oxygen, which is probably a cheaper deal than fitting your Maule with Oxygen! And if your Maule has a towhook you might be able to come to a special arrangement..

I got my diamond height at Deeside, 20,300 feet gain of height above the airfield. If any glider pilots would like to know how I dun it, it involved crossing from one bar to another not at the strongest lift place but at the weakest lift; less sink on the way to the next bar upwind. Magic!

[abgd]

Question... Why should it be dangerous to fly powered aircraft in places that gliders fly all the time?

Is it just that the powered pilots are less likely to know what they're doing? Or is it that the capabilities of the aircraft make them safer to fly in wave and ridge lift?

[thing]

Gliders have better performance and in general glider pilots have far better met appreciation than the average spammer. (I'm not a glider martyr by the way, I do power as well) By the way the wave height record in a glider is over 50,000 ft....

Both Aboyne and Portmoak will be glad to give anyone the benefit of their advice when it comes to wave (and there are probably no better in the world to give that advice). Also should you fly into Aboyne you will find the runway interestingly narrow. I seem to remember that a Chippy has 4 inches clearance either side of the wheels.

[abgd]

Hmm... My only gliding experience is with hang-gliders, but the only parameters in which my glider beats the powered aircraft I fly are stall speed, landing distance, economy and fun. Oh, to step off a cliff again and take the elevator ride straight up!

[thing]

A good open class glider will give you a descent rate of around 80 fpm at 60kts and Vne of over 150. As a mate of mine who has an ASW 22B said 'If you can see it on the horizon, you can glide to it.'

But then you can't stick a couple of mates in it and tell them that we're off to Land's End for the day out and other than utterly crap weather I can take us there and back safely.

[cats_five]

Gliders have better performance and in general glider pilots have far better met appreciation than the average spammer. (I'm not a glider martyr by the way, I do power as well) By the way the wave height record in a glider is over 50,000 ft....

Both Aboyne and Portmoak will be glad to give anyone the benefit of their advice when it comes to wave (and there are probably no better in the world to give that advice). Also should you fly into Aboyne you will find the runway interestingly narrow. I seem to remember that a Chippy has 4 inches clearance either side of the wheels.

PMK and ABO probably have the best advice in the UK, but the world? Probably not. There is a lot of wave flying in NZ and the Americas, and probably other places I don't know about.

I have no idea what the G limits on the average GA steed are, I do know that gliders are very strong (built to survive repeated field landings!) and also if you fly wave right, you are rarely if ever flying in the rotor once you've got into the wave - you are flying along the front of the wave bars, sometimes very fast, and a jump upwind is done where the wave looks to be running less strongly e.g. the clouds are smaller.

However, OP, you might well enjoy a visit to PMK or ABO as it will give you a very different flying experience and perspective. Gliders are also wonderfully quiet - both no engine noise, and very little wind noise - so you can talk to the chap in the back seat without needing headsets and so on.