

NTSB investigator Brian Rayner peers into the cargo door opening on the fuselage of the plane where three died. Three persons were killed in the plane and 3 persons were killed in one of the homes. (Photo by Michael S. Williamson/The Washington Post)

In the aftermath of the plane crash in Gaithersburg Monday, that claimed 6 lives, I noticed most news accounts dismissed weather as a possible cause.

“The weather — scattered clouds at 2,100 feet and a 7-mph northeast wind — [did not] appear to play a factor,” wrote the Post’s Ashley Halsey, for example.

More than likely, they’re right – the weather wasn’t a factor. But is there some remote chance that weather played a role? Two aviation experts I spoke to said yes, while stressing they believe investigators will ultimately determine the cause was something unrelated to weather.

So what exactly is the unlikely scenario that weather may have contributed to the accident? Icing – or the build-up of ice on the aircraft – which adds weight to the aircraft and disrupts the flow of air over the wings.

Although weather observations from Gaithersburg Airport indicated just scattered cloud cover in the vicinity around the time of the accident, there were light snow showers in the region before and after it, along with subfreezing temperatures, which could have, hypothetically, caused icing.

At 10:32 a.m., just 15 minutes prior to the crash, radar (below) indeed showed light snow showers in the region.

Capital Weather Gang readers reported flurries in Gaithersburg shortly after 11 a.m., not long after the crash.

Snowing in Gaithersburg. Doesn't seem to be sticking though. @capitalweather — Dave (@MrESQ_VT) December 8, 2014

Randy Bass, a certified consulting meteorologist who works in the aviation field, emailed me the following thoughts, speculating about the possible role of icing:

My first thought when I heard about it was that it could have been icing since my supervisor was teleworking in Frederick that day and [messaged] me about the flurries earlier … indeed there was a report of moderate icing at 5,000 ft just southwest of Frederick at 10:45 a.m., the exact time of the crash. Finally, the reports of the plane gaining then losing altitude before barrel rolling, as well as sputtering engines (ice in the engines?) could point towards icing since it would cause loss of lift. On the other hand, there were no other significant reports of icing, and even moderate icing shouldn’t be a problem as long as you don’t continually fly in it. Also, the pilot didn’t appear to report it or indicate any problems like that. Plus, lots of other things could cause the plane to act erratically, including bird strikes or being out of gas. As you probably heard there were reports of large flocks of birds in the area. Personally, I’m inclined to think it wasn’t weather related, but it certainly can’t be ruled out. One other thing to consider that bolsters the icing theory. I just read an article that said the plane almost stalled before crashing. There have been cases before where some of the instruments on the plane collect water and freeze up, including the speed indicator. In fact, I believe that’s what happened in the Air France [June 1, 2009] case. If that happened, the pilot would believe he was going faster than he actually was, and by the time the stall warning started it could have been too late to recover.

A second source, who is a current commercial pilot, sent me the following thoughts:

[G]enerally [flurries or light snow] alone should not pose a significant hazard to an aircraft that is certificated to fly in icing conditions. I will add that flurries or snow become a bigger issue when they build up on the aircraft surfaces of non-icing certificated aircraft or while on the ground, thus the need to be deiced and anti-iced. But according to reports, there were other smaller aircraft flying around that did not have an issue with the light flurries. I’m not saying it should be ruled out, because I don’t like to speculate ahead of what the National Transportation Safety Board releases, but just based on the information released so far, I don’t really see anything glaringly obvious about the weather that could be considered a primary factor to this accident. That said, if an aircraft gets slow, ice can exacerbate the problem and cause an aerodynamic stall at a higher than normal airspeed. Still, it’s hard to say if that’s what happened here. For all we know the airplane was completely clean of ice, which is likely based on the conditions.

The National Transportation Safety Board will review the possible causes of the crash and release a report some time next year.