What Do You Mean, They Went Inadvertent IMC? - Instrument Meteorological Conditions - Brief Article

Approach, June, 2001 by Michael K. Phillips

The title of this was my response when, as the unit safety officer, I heard that one of our crews had "punched in." Of all the times for it to happen, it occurred during a deployment to Bosnia, over mountainous terrain, and at night while wearing NVGs. If that weren't bad enough, the flight was a medevac mission with a patient on board. The two pilots had a total of about 800 flight hours; the pilot-in-command (PIC) had some additional civilian flight experience and was considered one of the more squared-away PICs in the company.

I used to consider inadvertent IMC a "self-induced emergency caused by pilot error." For the most part, I still think that's true, but I guess there are times when you just can't see the clouds. Or, if you're wearing NVGs, by the time you realize that you're in a cloud, it's too late to continue VMC.

I never gave inadvertent IMC much thought until that day. We're not supposed to and we have procedures in place in case we do it. Hardly anybody ever does anyway, so why worry about it? I've been in Army aviation for more than 11 years and had never been a unit when a crew had gone inadvertent IMC. The perfect track record had lulled me into a false sense of security. It made me to think it couldn't happen, or wouldn't happen. Not on my watch anyway.

We train our crews to avoid it at all costs. We tell them over and over, don't try to fly VFR in IFR conditions. It's dangerous. We've all seen the Safety Center posters showing the catastrophic results. If weather is bad, don't fly. If you launch and the weather gets bad, turn around and go back, or land and wait it out. Or, if you are trained, equipped, prepared, and proficient for IMC flight, request an IFR clearance from ATC and continue the mission IMC. Of course, that last option may not always be available in Bosnia, or on other deployments, depending on local Navaids and instrument approaches.

The question is, have we all been lulled into a false sense of security? We've all heard the old pilot joke, "If it's too bad to go IFR, we'll go VFR." To avoid going IFR, many of us have gone scud running. A Federal Aviation Administration publication(1) defines "scud running" as "pushing the capabilities of the pilot and the aircraft to the limits by trying to maintain visual contact with the terrain while trying to avoid physical contact with it."

I've had several encounters with deteriorating weather while flying VFR. Many times, I simply turner around and went home. On a few occasions, I radioed ATC and received an IFR clearance so I could continue the mission IMC. But I've never gone inadvertent. I've turned down countless missions (including medevac missions) because of poor weather. Somehow it's easier to refuse a mission while standing in the flight operations office than to refuse to continue to fly a mission while in the air. We all want to succeed in our mission, especially if that mission is to save a life.

There are times when a patient's only hope of survival may be via a flight on a military helicopter. Air ambulance units, like the one I'm in now, are frequently called upon to fly in poor weather and at a moment's notice. All too often, Dustoff crews will fly a medevac mission in weather that they wouldn't even consider flying in on a training flight. I've certainly been there, done that. The desire to succeed can easily turn into perceived pressure to complete a mission, particularly a medevac mission. That pressure is almost always self-induced and is felt by pilots and even non-rated crewmembers. Commanders will always support crews that turn down missions for safety reasons.

According to an NTSB study(2), unplanned entry into IMC is the single most common factor in fatal crashes involving emergency-medical-service helicopters. Because most of the inadvertent IMC accidents result in pilot fatalities, accident investigators can learn little about the events that lead to the accidents. In cases where pilots lived to tell their stories, it's like the Safety Center has been telling us all along: they tried to fly VFR in IFR conditions. They also felt pressure to accomplish the mission, in spite of deteriorating weather.

The Army has procedures that prepare us in the event that we do go inadvertent IMC. We brief procedures with the crew prior to every flight. The Aircrew Training Manual clearly states, step-by-step, what to do. Local SOP also provides guidance in case we accidentally punch in.

On the night when our crew went inadvertent, they did everything by the book, just like they were taught. The PIC briefed inadvertent-IMC procedures to the crew before the mission. The pilots got a valid weather briefing and had even updated it just before takeoff. The PIC had the only available instrument-approach procedure open and strapped to his kneeboard, and approach control frequencies were set in the radios. (The weather forecast had called for better-than-VFR conditions.)

About five minutes after takeoff, the pilots watched as the ground lights started to fade, flicker, and then disappear. They controlled the aircraft just like the ATM tells them and began the local inadvertent-IMC recovery procedures. At first, they felt fear, anxiety, and nervousness; the first 30 seconds were the worst. Once they knew that the aircraft was under control and they transitioned from NVGs to instruments, they felt much better. This crew was prepared for the worst when it happened. With the assistance of ATC, the aircraft broke out on final of an ILS approach and landed safely.