Gaithersburg, Maryland plane crash into powerlines

Friends in the D.C. area have been texting me tonight regarding a Mooney that landed in some powerlines near KGAI. From CBS:

A small plane crashed into power lines in Maryland, leaving two people dangling about 100 feet in the air, officials said. The crash knocked out power to thousands of people in the area.

A single-engine Mooney M20J crashed into wires near Montgomery County Airpark in Gaithersburg, Maryland, around 5:40 p.m. local time Sunday, according to the Federal Aviation Administration. The plane appeared to be intact as it was caught in a web of power lines about 100 feet in the air.

As of roughly 7:50 p.m., Montgomery County Fire and Rescue Service spokesperson Pete Piringer said the people aboard the plane were uninured. Earlier he said that they remained in a “very precarious situation,” as the wires were still energized. Utility company Pepco said that as of around 8:30 p.m. the lines had been deenergized.

How could this happen? Mooney pilots are usually pretty good! The plane departed from Westchester County, NY, according to ABC. So the task at Gaithersburg was an attempt to land. Where are these powerlines? Let’s check The Google:

The only tall high-voltage lines that I can see are about a mile from the runway, top left of the above image, rather near Giant Food. That’s quite a distance from the runway to be so low to the ground.

Let’s check the weather. 5:40 pm is 17:40 EST then add 5 hours and we get 2240Z. Here’s are the METARS:

KGAI 272156Z AUTO VRB04KT 1 1/4SM BR OVC002 11/11 A2945 RMK AO2 SLP987 T01060106
KGAI 272128Z AUTO 18003KT 1 1/4SM BR OVC002 11/11 A2945 RMK AO2
KGAI 272121Z AUTO 14006KT 3/4SM BR OVC002 10/10 A2945 RMK AO2
KGAI 272110Z AUTO 14007KT 1 1/4SM BR OVC002 11/10 A2946 RMK AO2
KGAI 272056Z AUTO 15004KT 2SM BR OVC002 11/10 A2947 RMK AO2 PRESFR SLP995 60003 T01060100 56050

Why isn’t there a METAR closer to 2240Z? It seems that the 2256Z observation would have come after the massive power failure. Here’s an observation from nearby Dulles Airport:

KIAD 272252Z 21011KT 1 1/2SM BR OVC003 11/11 A2945 RMK AO2 SFC VIS 9 SLP971 T01110106

Could part of the problem be that the altimeter in the Mooney wasn’t set correctly and, therefore, the instruments were showing the plane to be higher than it was? This is an irrelevant factor for an approach with a glide path, which KGAI has. They would have gotten fresh altimeter settings during the entire flight from Air Traffic Control. The departure airport, KHPN, had an altimeter setting of 29.64″ about one hour before accident. So if they’d taken off from HPN and never touched the altimeter they would have been (29.64-29.45)*1000 = 190′ lower than indicated. This kind of mistake resulted in an accident at KBDL to American Airlines 1572 (The NTSB report says that they were on a VOR 15 non-precision (no glideslope) approach.)

The weather was not improving dramatically after 2156Z (4:56 pm). Is it reasonable to land with only 1.25 miles of visibility and 200′ overcast? If you’re a two-pilot crew going into Dulles Airport with its idiot-proof runways and powerful approach lighting system that will cut through the clouds and mist… yes. In fact, the minimums for the ILS 1R at KIAD are 200′ ceiling and 1800′ of visibility.

What about at KGAI? Assuming that this airplane was trying to land, they’d be using the RNAV 14. With the latest and greatest WAAS-capable avionics, the weather minimums are 269′ and 1 mile of visibility. Touchdown zone elevation is 520:

So this would have been an attempt to do the an approach that the weather report suggested could not be accomplished legally. This is actually legal for Part 91 (private) flying, but is not permitted for airlines (Part 121).

On the third hand, had the pilot flown the approach correctly, it should have resulted in a safe landing on the runway even with weather below minimums. Based on my experience, the virtual glide path created by the WAAS GPS box is valid all the way to the ground. (And this was part of our airline training at a Delta subsidiary for ILS approaches; the glide slope (projected via radio waves from the ground) could be used as a reference even after breaking out from the clouds and being within 50′ or 100′ from the runway.) In fact, an autopilot could take the plane down all the way to the runway (would be a rough landing without a flare, but nothing that would be hazardous to the people inside the plane).

So the crash remains something of a mystery at this point. I would want to know if the Mooney (potentially ancient) had a modern WAAS-capable GPS for the RNAV 14 approach. If not, the weather minimum is 400′ ceiling and 1.5 miles of visibility and the challenge for the pilot is substantially greater.

This would be perfect for a Godzilla movie. Godzilla loves powerlines and he is often well-disposed to humanity so he could simply pull the airplane out of the powerlines and set it down on the runway.

Update: I found some relevant Air Traffic Control audio at LiveATC.net. Controllers often speak on multiple frequencies and I found half of a conversation on 128.7 in the archive block starting at 2200Z on 11/27 (so the media reports of a crash at 5:40 pm are probably incorrect; it would have been around 5:28 pm). LiveATC.net captured Potomac Approach, but not the Mooney or other aircraft (so it is likely that the exchanges were happening on a different frequency associated with Potomac Approach; a merged recording of 126.75, 125.52, and 133.85 contains some fuzzy responses from the planes/pilots). The Mooney’s tail number seems to end with “1RF” (One Romeo Foxtrot). At 9 minutes in, the controller suggests (gently) that the 1RF has not followed a previous instruction correctly. At 14:45, the controller says “if you’re able to land at Gaithersburg you can report cancellation…” (i.e., it was foreseen that the weather could be below minimums). At 15:55, a Pilatus PC-12 (“Kronos”) is also going to GAI. At 16:45, the controller mentions, probably to the Pilatus, that a Cheyenne went missed from GAI and was diverting to FDK. At 17:45, the controller acknowledges a communication from 1RF. At 18:30, the controller tells 1RF about traffic and tells 1RF to join the approach. At 20:15, 1RF is cleared for the approach (allowed to descend from previously assigned altitude). At 23:15, 1RF is told to switch to the advisory frequency at the untowered KGAI airport (“CTAF”; used for pilot-to-pilot communication). Just before 27:00 the controller uses the full call sign: N201RF, which is the registration for a 1977 Mooney. Unfortunately, this is to issue a low altitude alert. If indeed the Mooney had switched to the CTAF, the message would not have been heard. Just before 30:00, the controller says “it looks like they made it” regarding the Mooney, but tells the Pilatus that he is waiting to get a cancellation from the Mooney (can’t have two airplanes doing instrument approaches at the same untowered airport at the same time).

My best guess is that the conversation was on 126.75, but the receiver that feeds LiveATC.net is not well-positioned to hear low-altitude planes near KGAI.

Second Update: presidentpicker in the comments below gives us an overlay of the Flightaware ADS-B 3D track and the approach. The tracklog ends at 5:27:20 pm and sadly infers an arrival:

Pilot readers: Before we escaped the Land of Lockdown for the Florida Free State, KGAI was my most common destination airport for trips into D.C. My personal rule was that if the weather wasn’t great I would land at Dulles instead. “Not great” meant winds of more than about 20 knots unless straight down the runway, ceiling below 400′, or visibility of less than 3 miles. I would also go into Dulles if I were arriving after the KGAI FBO closed and I wanted a rental car. The fees at Jet Aviation Dulles or Signature for a single-engine piston aircraft were actually quite reasonable. It’s great to be a skilled pilot, but it is even better to set up a situation in which skills are not required. And there’s nothing wrong with doing an approach to minimums, especially if you’ve set up a two-pilot crew in your little Cirrus, but it doesn’t make sense when one of the world’s largest airports is only 5-10 minutes farther from your ground destination.

The Dulles photo above was taken just before landing at KGAI last week:

We departed Torrance, California in the Robinson R44 Raven II shown above and landed at Gaithersburg on November 21, 2022. There were a few stops in between…

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