I cannot believe people contemplate flying below a 1000ft cloudbase VFR. They must have a death wish.
Of course such a simple statement is wrong.
It all depends on vis, terrain, due diligence before the flight, etc.
It can be far safer to fly at say 800ft, from the coast to an airfield just a bit inland, with flat terrain, after a descent into VMC over the sea, than descending to 800ft over land which requires much more planning with a topo map, etc.
And there are occasions in a small plane where it is better to fly VFR at lower levels than IFR. If you risk icing higher up, but have no de-icing capabilities for example. Or if you can use the flexibility that VFR grants you to avoid a weather system by flying around it, whereas the IFR routes would take you through it. You could request a different route from ATC but if they are busy you may not get what you need or find yourself holding somewhere.
In view of some recent prangs, I thought I might as well bump this thread with some comments:
There are two schools of thought: one is to advise “don’t do it”. That’s all very well, but it’s evidently as futile as telling teenagers not to have sex. People will scud-run anyway, even if we have instrument ratings. A few scud runners die. Most don’t.
The other school of thought is to think about how to do it without dying and then practice, and then plan and be ready for the eventuality on any MVFR day. Most of the good advice is covered above, especially in @mmgreve’s post #39 but is there a scud-running “guide” on the lines of PPL/IR’s paper on DIY cloud breaks, for example?
A EuroGA project for the current period of “house arrest”, perhaps?
Attitudes toward scud running vary with the locale/country. There are places where you have little choice if you’re going to fly much at all. It is dangerous, especially for pilots who lack experience in doing it; risks can be reduced, somewhat controlled if you know what you’re doing and the environment is one where it is less unusual.
I don’t like it, but have done it when ceilings were lower than forecast on long VFR x-countries. Never through mountainous areas, but even gradually rising terrain or a line of hills can create issues for you.
I define scud running as flying below a ceiling under 1000 feet. A 1000 foot ceiling feels perfectly comfortable over flat terrain.
Another big issue is visibility. Excellent visibility with 800 foot ceiling is one thing. Crap visibility with 1000 foot visibility is worse. 500 feet over the water is fine
It is all so dependent on the context; position of alternates; weather trend (are you flying into worse or better weather?); and terrain (rising or falling). If you haven’t considered all of these factors, you shouldn’t be doing it. I try always to leave myself an out. When I see it might fade, I fold—I take my out and wait in
The ground.
I’ve certainly been guilty of pushing the limit early on in my flying career when I thought I was invincible. I look back at some trips and flights now and think: what were you thinking? But generally I would agree that low vis is the killer rather than low ceilings, per se. Many times it has been 800-900ft ceilings but 10 mile visibility under the layer. Especially common after heavy rain storms have passed through. But a 3 mile visibility starts getting my attention and a 1 mile vis, which is legal here in class G, is downright scary to me. I don’t know how those Alaska bush guys do that day and day out. Takes balls.
Jacko wrote:
There are two schools of thought: one is to advise “don’t do it”. That’s all very well, but it’s evidently as futile as telling teenagers not to have sex. People will scud-run anyway, even if we have instrument ratings. A few scud runners die. Most don’t.The other school of thought is to think about how to do it without dying and then practice, and then plan and be ready for the eventuality on any MVFR day. Most of the good advice is covered above, especially in @mmgreve’s post #39 but is there a scud-running “guide” on the lines of PPL/IR’s paper on DIY cloud breaks, for example?
Of course don’t do it: no one can last that long, or make it short not too fast and not too slow and be ready to backtrack/climb (I mean MVFR scuds running not sex 
)
The guide will be useful but I expect it to be very short as the flight over any piece of land or terrain in 1.5km visibility
Also, there are no flying skill to learn when visibility is less than turn radius and climb rate at your flying speed
The reason why many instruments pilots have died in MVFR scud running it is because they overestimated aircraft turn/climb performance at high cruise speeds, things like you need 9000ft diameter for rate 1 turn, 4000ft on a 45deg turn, 5000ft distance to climb 500ft will go unnoticed in the heat of the moment doing 140kts in 1.5km visibility, this can happens even in sunny days with 10km visibility but you need mountain at 1.5km nearby…
I read this thread and had a bit of think about what, for me, might define scud running.
When you need to descend to remain VMC, but based on the terrain you’re not comfortable with making that descent. That’s my definition.
Context is everything. Aircraft, terrain, what you know about the weather, destination, etc.
WhiskeyPapa wrote:
500 feet over the water is fine
Hmm. In terms of obstacle clearance – probably.
But in the case of a VFR only pilot? Even if visibility is reported as >10km, the clouds and the sea can merge into one same-coloured milky bubble. I’ve flown over the sea on days with clear skies even, where vis was reported >10km, but the view outside was a milk bowl – whichever direction you looked, everything was basically the same uniform colour and as the day was calm there were no discernable ripples on the sea, and no visible horizon – would be challenging conditions for anyone who’s never flown in IMC before. But with a 500’ ceiling – especially if the weather was calm, it would be very easy to lose control and not have enough sky left over to recover.
I hope my post was not meant to be a “guide” to scud running or in ant way an encouragement to launch in questionable weather. It is just a realization that pilots at times find themselves in situations they had not planned for and if it ever happens to you, I recommend you to fight the urge to get away from the ground as you will be trading ground clearance for visibility and visibility is far more important. It is a little like urging VFR pilots to trust the instruments rather than their seat-of-pants if they find themselves in IMC. My other recommendation will be to slow down and drop some flaps.
I don’t think a guide is a good idea, as it indicates a “how-to” approach. I would by far prefer that instructors show it to clients on the same lesson where they practice the 180 IMC turns.
The reason why many instruments pilots have died in MVFR scud running it is because they overestimated aircraft turn/climb performance at high cruise speeds, things like you need 9000ft diameter for rate 1 turn, 4000ft on a 45deg turn
I think you may have hit the nail on the head. Are some “instrument pilots” really so devoid of common sense, or so determined to fly like their autopilots, or so afraid of the ground, that they just yank and bank, trying to maintain altitude? We can turn in a few hundred feet if we unload the wing, but it’s not part of the usual checkrides, so we have to learn it independently.
When you need to descend to remain VMC, but based on the terrain you’re not comfortable with making that descent. That’s my definition.
And I think it’s a pretty good definition. And that may be the time to lose another 200 ft in a 180 turn.
Some other points: watch for poles or pylons, not wires. Wires in mountains may be higher than the pylon. If in doubt about flying under a wire with marker balls, don’t. Sometimes there’s an unmarked wire below.
I don’t agree about never scud running in mountains. Lots of people do it and don’t die. Many times the cloud “lid” on a valley is stable with good viz 200 ft below. Just don’t fly in the middle of the valley.
