Safety Check – Surviving an IIMC Event
I recently observed one of my friends, a fellow CFII, helping a pilot perform multiple instrument approaches. For the purposes of this article, I’ll call the pilot “George” and the instructor “Sam.” Sam informed me George had faced a very scary experience the previous week after encountering inadvertent entry into instrument meteorological conditions (IIMC). George wanted to log some additional time practicing in simulated instrument conditions.
According to the International Helicopter Safety Team (IHST), IIMC occurs when you lose your horizon reference and/or visual contact with the ground because of deteriorating weather.
I hope that by sharing George’s experience with IIMC, I might encourage you to develop a plan of action or to seek out additional training should you ever find yourself in a similar situation.
George is a licensed private pilot with about 300 hours of rotorcraft time, but he has yet to earn his instrument rating and has very little time of simulated IFR.
Last month, George needed to reposition his helicopter to a maintenance facility about 100 miles from home base. It was still dark out on that mid-December morning, creating marginal VFR conditions, with a ceiling at 1100 feet overcast and 5 sm.
George would tell you he’s normally a conservative pilot and only flies when the weather offers good VFR. However, he said he felt additional pressure to make the trip that day because his helicopter was due for a scheduled maintenance inspection and a few minor discrepancies. Plus, terminal area forecasts projected conditions would improve along the flight route throughout the morning, convincing George it was safe to embark.
I’ve harped on the danger of self-induced pressure in past Safety Checks, but it bears repeating. Don’t talk yourself into continuing flying if you feel unsafe.
The route called for George to travel through Class D airspace. George flew to a spot about ten miles north of the Delta airspace and requested clearance to enter. The ATC tower denied him, alerting him that the field was IFR, and an aircraft was on approach. George made a slight heading change, but as he did, he noticed that the overcast had continued dropping since he departed his private hangar.
Technically, George was still legal according to FAR 91.155 (b), which requires at least one mile of visibility during the night (or a half mile during the day), but that didn’t help reduce his growing discomfort with the deteriorating weather. Pushing those thoughts aside, George noted he was more than halfway to his destination and didn’t want to turn back. He chose to press on. It was a decision George admits he would later regret.
George’s landing light soon picked up the bases of clouds whizzing by him at more than 100 knots. He lowered the collective to reduce his forward speed, and in a flash, found himself in IIMC. With his heart racing, George lowered the collective even more. His airspeed indicator showed 5-10 knots, and the VSI’s sink rate peaked at more than 1500 feet per minute.
It’s been said, “Once you encounter IIMC, the ground is no longer your friend!” I would agree. Accidents from IIMC result in a sobering fatality rate. NTSB data from 2011 show 45 of the 52 IIMC accidents from that year resulted in death.
Fortunately, George avoided becoming a statistic. After breaking out of the bases, he found himself in an open field, a tree line straight ahead of him, and an altitude less than 150 feet above ground level. George climbed to a safe altitude, then immediately reached out to the nearby tower operator, and worked out a route that was VFR. He returned home later that day, safe and sound.
He might not have realized it, but George actually followed the International Helicopter Safety Team’s recommended four Cs for IIMC immediate action: Control the aircraft, enter a controlled Climb, set a safe Course, and Communicate with ATC (more information can be found in this document).
Even so, George felt quite shaken up afterward. The above document describes IIMC encounters as “some of the most demanding, disorienting, and dangerous conditions a pilot can experience.” George ultimately reached out to his flight instructor Sam and told him all about what happened. Sam and George agreed George would benefit from comprehensive IIMC training, including both flight and ground school instruction on IIMC recovery.
If you have yet to take IIMC training yourself (or haven’t practiced in a while), I highly recommend you schedule some time with an instructor. Your immediate actions in the first adrenaline-filled moments after encountering IIMC could determine the difference between recovery and risking a 14% survival rate.
Randy is a dual rated Airline Transport Pilot with 13,000 flight hours in airplanes and helicopters. He has type ratings in the BE400 and CE500. Randy has been a rotorcraft Designated Pilot Examiner representing the Grand Rapids FSDO since 2014. Currently he works for Sweet Helicopters, a northern Indiana Part 135 air carrier operator and serves as the Airport Manager of the Goshen Municipal Airport.
About Enstrom HelicopterFrom Rudy Enstrom’s early designs in 1943 to initial testing in a Michigan Quarry in 1957 to aircraft operating on six continents, Enstrom Helicopter Corporation has maintained a reputation for safety, value and performance. Based in Menominee, Michigan and proudly made in the United States, Enstrom has a rich history for design innovation. The goal is to provide helicopters to the customer’s exact specification and deliver support and maintenance worldwide.