That is the “headline” on the NASA ASRS Callback bulletin 278 for November 2002.
This is one of the reports submitted to the ASRS:
“…We were going to have to find the runway regardless of the weather.”
This “chilling” statement reflects the gravity of the situation encountered by an instructor and student in an ice-encumbered Cessna 172. Knowing the limitations of one’s aircraft and having a respect for the forces of nature are two universal lessons learned by the instructor who submitted this report.
"The (Cessna 172) began to accumulate light rime ice in cruise at 10,000 feet… Icing became increasingly heavier until…we were having difficulty maintaining altitude. Departure (said) he needed us to maintain 10,000 feet. I told him we were picking up ice and requested vectors (to the) ILS Runway 35 at XXX… We checked in with the Tower (and we were) cleared to land. Icing was moderate at that point. We had full throttle at 70 KIAS and (we were) descending 400 feet per minute. We were unable to maintain approach minimums, and at one point Tower said, “You probably know this, but I’m getting an altitude alert…” We briefed the approach and knew we were going to have to find the runway regardless of the weather… We saw the approach lights at about 400 feet AGL, almost 500 feet below the localizer approach minimums. We landed without incident (with two inches of ice). The approach and tower controllers were extremely helpful.
Causes: We took off into forecast icing conditions… I thought if we could get up high enough (10,000 feet) we could fly over the icing layer."
CALLBACK concludes the report with:
“Even a very thin layer of ice on the leading edge and upper wing surfaces can cause a dramatic loss of lift and increase in drag. With ‘two inches’ of ice, these pilots were lucky to be near an airport.”
I say that they are lucky to have survived.
After their experiece, I wonder what they would tell the pilot who chooses to launch into icing conditions in any airplane, e.g., the Cirrus SR20 or SR22, not certified for fllight in icing conditions.
Yesterday’s LA Times contained a story about cloud seeding in Colorado to increase the snow pack for both the ski resorts and reservoirs. The article didn’t mention whether or not there was a requirement for clouds to be in the vicinity for it to work. Does this mean that if a clear sky can be made to snow that icing can occur WITHOUT any visible moisture?
You MUST have clouds for this to work. The “seeding” merely makes the tiny water droplets stick together to male big droplets so they will fall out of the sky as rain. You need a moisture source (clouds) to start the process.
You MUST have clouds for this to work. The “seeding” merely makes the tiny water droplets stick together to male big droplets so they will fall out of the sky as rain. You need a moisture source (clouds) to start the process.<<
To complete the thought: AND, this means you can’t get ice on your airframe in clear air
You MUST have clouds for this to work. The “seeding” merely makes the tiny water droplets stick together to male big droplets so they will fall out of the sky as rain. You need a moisture source (clouds) to start the process.<<
In reply to:
To complete the thought: AND, this means you can’t get ice on your airframe in clear air.
Dave,
Sort of - in truly clear air, yes… but I believe that you can get very bad structural icing in VMC, if you encounter freezing rain (like when you’re in the cold air below an advancing warm front). Visibility might be good, and you might not be in cloud at all… so if you’re in clear air with no precip, you’re OK, but merely being in VMC (not in cloud) is not a guarantee of no ice.
Mike:
You are correct. The warning for ice in the winter always calss for “chance of ice in clouds and PRECIPITATION”. The reason for that is the fact that rain can freeze on your airframe if you are flying in air below freezing. But you WILL NOT get ice flying in clear air unless it is freezing rain. And then, the air is not really clear.