If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
Descending through a thin icing layer
Let's say you take off on a long cross country with no forecast of icing. By
the time you arrive at your destination, a 2,000-foot layer exist below you with temps of 30 F. You are getting low on fuel. Is it legal to descend through the thin layer even if you are in an airplane without known icing? |
#2
|
|||
|
|||
"Wyatt Emmerich" wrote in message ... Let's say you take off on a long cross country with no forecast of icing. By the time you arrive at your destination, a 2,000-foot layer exist below you with temps of 30 F. You are getting low on fuel. Is it legal to descend through the thin layer even if you are in an airplane without known icing? Who knows? Better play it safe and run out of fuel above the clouds. |
#3
|
|||
|
|||
icing is a safety issue....flying w/o fuel is also a safety issue.
if you know you're about to run out of fuel (you should have .5 hr reserve if you're a stickler), and if you attempt to fly w/o knowing how far you'll have to go to get vfr descent...you're taking a major chance. also, going thru a cloud layer or rain is not automatic an automatic fall to the ground like stone situation. in MOST cases one gets into trouble because of flying quite a while in icing conditions...ice layer builds up...drag increases...airspeed decreases...and eventuall stalls. in your scenario...if you've above the airport AND you're running short on fuel...setting yourself on the downwind to the active and descending should be ok. land w/o extending the flaps. others might disagree...but my point is weighing the two situations - icing when you're over the airfield w/ running out of fuel. bman. p.s. com'n lets build up this newsgroup!!! "Wyatt Emmerich" wrote in message ... Let's say you take off on a long cross country with no forecast of icing. By the time you arrive at your destination, a 2,000-foot layer exist below you with temps of 30 F. You are getting low on fuel. Is it legal to descend through the thin layer even if you are in an airplane without known icing? |
#4
|
|||
|
|||
Wyatt Emmerich wrote:
Let's say you take off on a long cross country with no forecast of icing. By the time you arrive at your destination, a 2,000-foot layer exist below you with temps of 30 F. You are getting low on fuel. Is it legal to descend through the thin layer even if you are in an airplane without known icing? If there is no forecast for icing conditions, then it appears you are legal according to the FAA. However, if you are low on fuel, then declare and emergency and you shouldn't have a problem with legality at that point ... assuming you really do have the grounds for the declaration. Matt |
#5
|
|||
|
|||
"Wyatt Emmerich" wrote in message
... Let's say you take off on a long cross country with no forecast of icing. By the time you arrive at your destination, a 2,000-foot layer exist below you with temps of 30 F. You are getting low on fuel. Is it legal to descend through the thin layer even if you are in an airplane without known icing? If you have a safe alternative, then descent through known icing-conditions would be illegal in that scenario. But if it's the only way you can land without risking fuel exhaustion, then you use your emergency authority to override the regulations. |
#6
|
|||
|
|||
"Bonanza Man" wrote in message ... icing is a safety issue....flying w/o fuel is also a safety issue. if you know you're about to run out of fuel (you should have .5 hr reserve if you're a stickler), You mean .75 hours unless you are a helicopter, I guess I am a stickler! Sec. 91.167 - Fuel requirements for flight in IFR conditions. (a) No person may operate a civil aircraft in IFR conditions unless it carries enough fuel (considering weather reports and forecasts and weather conditions) to -- (1) Complete the flight to the first airport of intended landing; (2) Except as provided in paragraph (b) of this section, fly from that airport to the alternate airport; and (3) Fly after that for 45 minutes at normal cruising speed or, for helicopters, fly after that for 30 minutes at normal cruising speed. |
#7
|
|||
|
|||
"Wyatt Emmerich" wrote
Let's say you take off on a long cross country with no forecast of icing. By the time you arrive at your destination, a 2,000-foot layer exist below you with temps of 30 F. You are getting low on fuel. Is it legal to descend through the thin layer even if you are in an airplane without known icing? No, it's not legal. However, since you are low on fuel and above an icing layer, you are in an emergency situation. You can thus ignore the prohibition on operating in known icing conditions (assuming your airplane has one) and descend anyway, since that's what's required to meet the emergency. Your condition is EXACTLY the same as that of a VFR pilot who relied on a forecast of clear skies over his destination, went over the top, had the forecast go bust, and is now trapped above a solid layer. The only difference is that he's more likely to come out of this unscathed than you. Michael |
#8
|
|||
|
|||
Not sure I agree with this - assuming the 2000 foot layer is not too low
AGL, you can bomb down through it in a little over a minute. Although it is possible to accumulate enough ice in a minute to affect flight, it is pretty unlikely. The key is not to hang out in the ice. For example, if the ice is at the same level as the IAF you may want to modify the approach and make it significantly steeper or shallower, depending on the surrounding terrain and altitudes. This happened to me in San Marcos once. I just got below the ice and flew a low visual approach. ATC was very cooperative. Michael "Michael" wrote in message om... Your condition is EXACTLY the same as that of a VFR pilot who relied on a forecast of clear skies over his destination, went over the top, had the forecast go bust, and is now trapped above a solid layer. The only difference is that he's more likely to come out of this unscathed than you. Michael |
#9
|
|||
|
|||
"Wyatt Emmerich" wrote:
Let's say you take off on a long cross country with no forecast of icing. By the time you arrive at your destination, a 2,000-foot layer exist below you with temps of 30 F. You are getting low on fuel. Is it legal to descend through the thin layer even if you are in an airplane without known icing? The basic thread of legality is that the FARs say you cannot do anything with the POH says is prohibited, and modern POH's for planes which are not approved for icing have a statement along the lines of "flight in known icing conditions is not approved". There's nothing in there which differentiates between conditions which were forecast to exist at the time you did your pre-flight planning and conditions which unexpectedly popped up during the flight. That being said, section 91.3(b) allows you great leeway in dealing with emergencies: "In an in-flight emergency requiring immediate action, the pilot in command may deviate from any rule of this part to the extent required to meet that emergency." Notice the "to the extent required", however. You can do anything you HAVE to, not anything you WANT to. So, is this an emergency? Yeah, stuck above a 2000 foot icing layer while low on fuel in a no-ice airplane sounds like an emergency to me. I assuse by "low on fuel" you mean you don't have enough to get to someplace else. If I was stuck in such a situation, I would declare an emergency to make sure ATC knew my predicament. I would get them to solicit pireps from people in the air right now to make sure I knew where the floor of the clouds were. Then I would get a clearance to descend, pilots discretion, to an altitude known to be below the clouds. Then I would get down though the layer as fast as I possibly could. Pitot heat on, carb heat on, enough engine power to keep the carb warm, and push the nose down. In smooth air, I'd let the airspeed climb well into the yellow arc. Gear down in a retract will help get you down faster. You should be able to get 1500 fpm down with no trouble. It's hard to imagine anything could happen to you in the time it takes to puch through a 2000 foot layer at that descent rate. A slip or steep turn will add drag too, but I'm not sure I'd advise either of those in a high-speed IMC descent. I'm sure some people will poo-poo the idea of declaring an emergency. Well, there's two reasons for doing so. One is that it gets you the legal authority to violate the POH. The other (more important in my mind) is that it makes sure ATC knows what's up. If you were to just say "request 4000", and ATC gave it to you, you would be in a pickle if in the middle of your descent, the controller came back with, "ammend altitude, maintain 6000 for now, I'll have lower for you in 5 miles". But, the biggest piece of advice is to NOT get into such a situation to begin with. Make sure you've got enough fuel to get to an alternate, whether it's legally required or not. And make it a real alternate, not a paper one. An alternate 5 minutes away from your destination is a stupid alternate because whatever weather is happening at one is likely to be happening at the other at the same time. Also, keep up with the weather during the flight. On a long X/C with any significant weather at all, I'm talking to flight watch once an hour to get weather updates. Getting a weather update is usually the first item on my agenda once I'm settled into cruise. If the forecast goes bad, the sooner you know about it, the sooner you can do something about it. |
#10
|
|||
|
|||
Roy Smith wrote:
"Wyatt Emmerich" wrote: Let's say you take off on a long cross country with no forecast of icing. By the time you arrive at your destination, a 2,000-foot layer exist below you with temps of 30 F. You are getting low on fuel. Is it legal to descend through the thin layer even if you are in an airplane without known icing? The basic thread of legality is that the FARs say you cannot do anything with the POH says is prohibited, and modern POH's for planes which are not approved for icing have a statement along the lines of "flight in known icing conditions is not approved". There's nothing in there which differentiates between conditions which were forecast to exist at the time you did your pre-flight planning and conditions which unexpectedly popped up during the flight. That being said, section 91.3(b) allows you great leeway in dealing with emergencies: "In an in-flight emergency requiring immediate action, the pilot in command may deviate from any rule of this part to the extent required to meet that emergency." Notice the "to the extent required", however. You can do anything you HAVE to, not anything you WANT to. So, is this an emergency? Yeah, stuck above a 2000 foot icing layer while low on fuel in a no-ice airplane sounds like an emergency to me. I assuse by "low on fuel" you mean you don't have enough to get to someplace else. Assuming that you got low on fuel through ATC delays, a fuel leak or something else largely out of your control. To me, getting low on fuel in deteriorating weather is preventable and doesn't thus constitute a bona fide emergency. It constitutes stupidity. I wonder if the FAA would really buy the emergency authorization argument for a pilot who had flown past airports that had fuel. I have to admit, if I was the FAA or an NTSB administrative judge, I don't think I'd buy it. Matt |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
FAA letter on flight into known icing | C J Campbell | Instrument Flight Rules | 78 | December 22nd 03 07:44 PM |
Supercooled Water - More on Icing | O. Sami Saydjari | Instrument Flight Rules | 50 | December 11th 03 01:20 PM |
FAR 91.157 Operating in icing conditions | O. Sami Saydjari | Instrument Flight Rules | 98 | December 11th 03 06:58 AM |