Sunday, October 22, 2006

How to Scud Run

When told that it is dangerous to fly at a low altitude under an overcast or broken sky, some pilots go out and fly at a low altitude under a ceiling of clouds with marginal visibility. I did it myself just the other day with a CFI candidate, pretty much right after the GA accident in New York. No, I'm not crazy and I'm not big on taking risks. And I decided it was time to reveal my personal tips on How to Scud Run Without Killing Yourself.

If you are going to scud run (fly at a low altitude under an overcast or broken sky), there are several things you need to do.

First, know that you have chosen to do something inherently dangerous and, this part is important, admit it to yourself. Bravado and braggadocio are for nut jobs and pilots soon to be selected out of the gene pool. Now that you have accepted that you are heading into the danger zone, it's time to start evaluating and planning.

Scud running requires a clear idea of where you are going and how you plan to get there. Let's say you have both a surface weather observation and a terminal area forecast for your departure and arrival airports. That's great, but what about the area in between, the area that is most crucial, the area where you may come close to terrain, the area where there is no controller, no radar contact, and no runway? This is where you need to use all available information - satellite photos, pilot reports, and your knowledge of local weather patterns - to decide how best to get from point A to point B.

Once you have a planned route to fly under the overcast, come up with Plan B - where you will go if the route you want to fly is not passable. And while you're at it, how about a Plan C? The easiest Plan B is to just turn around and return, assuming the weather conditions haven't deteriorated, and it's the plan many pilots never seem to consider. Truth be told, some pilots seem so intent on continuing along their planned route that it's almost like they want to come to grief.

Don't let your Plan B consist of hoping to find a hole in the ceiling and climb through it to VFR conditions unless you have some really good evidence that this is indeed a possibility. Wishing doesn't make it so.

It's also foolish to assume that Plan B will be to ask for and receive an IFR clearance to climb to VFR on top if you get in a jam. ATC may be able to grant this request, but then again they might be too busy or you might be below radar or radio coverage. If ATC does agree to help you out, they may ask you "Can you maintain your own terrain and obstacle clearance until reaching some altitude?" The bottom line is never assume that an IFR clearance will be available for you.

Speaking of weather, who is? But if I were, you should be interested in the overall weather pattern. If the weather is marginal VFR, are things going to get better or worse, and how quickly? If you're going to scud run, it's best to be headed toward better weather conditions or, at the very least, to have a stable weather pattern. If the weather isn't going to cooperate, file an IFR flight plan or stay on the ground.

One you are airborne, pick an altitude that will give you adequate terrain clearance and legal visibility and cloud clearance. Then fly that altitude! Your eyes are going to be outside a good part of the time while scud running, so being able to accurately fly a predetermined altitude is an important skill. If your predetermined altitude starts to take you into the clouds, don't be overly optimistic. Instead, reevaluate the situation and consider turning around or implementing Plan B.

If you have terrain awareness features on your panel-mounted or handheld GPS, by all means use it. But don't fixate on it.

Don't scud run in areas where you don't know the terrain and where you don't have an understanding of the local weather patterns.

In busy terminal areas you should keep in mind that if you have chosen to scud run, there are probably a bunch of other pilots who have made the same choice. You and your scud-running brethren will be squeezed in to a thin layer of usable airspace and face the chance of coming into close physical contact.

If you find yourself maneuvering in tight quarters, slow the plane down to a slow cruise. Slowing the plane down makes things unfold more slowly, giving you time to think, make decisions, or at least react to what's happening. A slower airspeed gives you the ability to keep your radius of turn small. A 30 degree bank angle at 90 knots is going give you a higher rate of turn and a smaller radius of turn that blasting along at 130 knots.

Oh, and I don't scud run at night.

Finally, scud running can be a seductive experience. Do it successfully a few times and you might start thinking it's a piece of cake. Just remember that like airframe icing encounters, no two scud running adventures are the same. What worked one time, might not work the second time.

And if you have your tips or advice for reducing the risks of flying in marginal VFR, please chime in.


Eric Gideon said...

These are good tips, and they echo my (limited) real-world experience with scudrunning.

Systems like XM WX and resources like flight watch are worth keeping in mind too. The weather doesn't always follow the TAF - those forecast improving conditions could never show up. It's something I see all too often when I fly back home in Seattle.

Colin Summers said...

The only time I seriously planned and flew a flight with a low ceiling was in the spring, from Santa Monica up to San Luis Obispo.

I made sure I had a lot of alternates. I knew every airport along the route, so that if I was turning back or dropping down to sit it out I had a feel for my options. At each point along the hour twenty minute flight I thought, "Okay, now it's Santa Barbara."

I always get flight following and even when radar contact was lost, I kept listening so that I was more aware of the traffic in the area.

The biggest lesson it taught me was not to rely on the XM weather in my G1000. We were approach KSBP and it was reporting IFR on the computer. Even Santa Barbara approach said it was IFR and what did I want to do? I was ready to land at Santa Maria (KSNX), but my wife said she want to *look* at SBP just to see the area that we would be heading up to later in the afternoon.

So with the controller's blessing we continued north to take a look. (We had plenty of fuel to fly all the way back home if we wanted to.) There were certainly some clouds around the airport, but the ATIS actually was reporting MVFR. I called the tower when we enter the airspace and the tower cleared us to land VFR, as long as we could hurry down ("Direct to the numbers, I have a regional jet on a four mile final...").

It was actually a flight that kicked my IFR training into higher gear, because it was a *very* think ceiling (two hundred feet at some reports), and it seemed like I should have been able to pop up and down through it.

Aviatrix said...

Over much of my world, there is no such thing as an ATC IFR clearance. You verify that you have an alternate and IFR fuel, you change the transponder code to 1000, you make a call to traffic on 126.7, and you haul back on the yoke, levelling out an appropriate altitude of flight.

The risks here are that if the weather s too low to scud run, it's too low to get into your destination on the approach, because there are no ILSes.

Also you didn't mention towers and guy wires. Many an airplane has ended up wrapped around them, and they are not visible in time to keep yourself from being wrapped around them. You have to know where they are in your area and have a clear plan for avoiding them.

John said...

I agree that XM weather and even the ATIS reported for an airport can be very misleading - the weather can be much better than reported, or much worse. When scud running, the safest bet is to assume the worst rather than be overly optimistic and assume the best.

Good point about the towers and such, Aviatrix. In remote, sparsely populated areas, towers and cables can be found in river gorges and valleys. In my neck of the woods (read "densely populated area"), towers and obstructions are being introduced at an alarming rate. So if you're flying so low that you're concerned with these human-made obstructions in my neighborhood, it's likely that you're already in a bad, bad way. Or you're flying a helicopter!

Sam said...

Good advice, John. Too many pilots have never been told how to scud run properly if they're going to do it, they've just been told DON'T do it. A good many airplanes and pilots have been lost scudrunning, but it wasn't because they did so, it was because they violated the rules of the game that you just layed out (ie continuing even when you cannot maintain legal terrain and cloud separation). I generally told my students that scudrunning is a dangerous game that requires having a few outs in your pockets at all times. Once the outs start disappearing, it's time to get on the ground.

requin said...

Sorry but I can't agree with what I read here. There are good reasons pilot are told not to Scud run. I am writing from Switzerland and I am a SEP PPL with a mountain land (wheel / ski) rating. We loose too many pilots every year in and around the Alps who are trying to scud run to destination. Here in Europe, it is much more difficult and expensive to get an IR rating so the majority of pilots fly VFR.
The only advice about scud running should be do it with your favorite instructor (IR rated) with a well equiped airplane.
Ah and just never to do it in moutaneous terrain where you are not familiar with every bit of the terrain.

John said...


I agree that one should err on the side of caution, which is why my piece included a variety of strategies for 1) making the decision whether or not to even attempt to scud run and 2) having options what will reduce the risks.

Having an instructor and a well-equipped plane is no guarantee, as witnessed by the Cirrus accident in Manhattan.

Stan said...

Another tip: Plan your route options along roads/highways or canals, whenever you can.

1. It facilitates orientation and reduces navigation workload. However cool your GPS equipment may be, it keeps you from looking outside, requires mental resources to apply what you see on the display to the real world outside and gives you no reliable information about your hight above ground.

2. It improves obstacle awareness (provided you check for and mark all relevant obstacles before you go!) because you have a very well defined route instead of a corridor which may be a couple of miles wide depending on your nav equipment and abilities.

3. It makes turning around and going back to your origin much easier if necessary.

4. If everyone stays on the right side of the road/canal (as is common practice at least in Europe where I live) the chances of collisions are greatly reduced (plus it's easier to keep the road/canal in view from the pilot's seat).

5. Roads/canals might cut through hills or ridges, providing the required space between ground and cloud base.

Don't forget to:

1. Check for any tunnels in advance. They're obviously dangerous when following a road. Even if you don't crash into the rising terrain in low visibility, you are likely to lose track of the road and get lost.

2. Check NOTAMS for recently erected obstacles not yet included in your chart!

And finally, like Requin wrote: Don't try scud runing in the mountains!