I realize there is a separate thread on the big storm, but thought it would be worth a separate thread to explain a bit about ice.....

Last night's schedule was cancelled due to the ice pellets. When we operate in winter weather we generally are able to de-ice and anti-ice the aircraft. The de-ice procedure uses a chemical to remove any contaminants from the aircraft surfaces. Anti-ice uses a separate chemical to prevent re-formation of any contaminants.

We use different chemicals depending on the type of precipitation, and have charts that define the amount of 'holdover time' from time of application until the aircraft has to be re-treated. With snow, light snow, etc. we are generally able to see holdover times of 25 minutes, 40 minutes, etc.....it is all dependent on the rate of precipitation, outside air temperature, etc.

With ice pellets and freezing rain the holdover time is 0 minutes. Essentially, as soon as the application is made, you are not legal to takeoff. If last nights storm had just been snow, the operations would have been able to continue. As soon as it turned to ice......it was a matter of shutting down the system, and gearing for a re-start today.

It's frustrating on everyone. I would have preferred to have been typing this from Stockholm today, but get to fly a rescue flight down to Orlando later this afternoon. Keep your chins up, and hope to see 216 of your smiling faces getting off my aircraft later this afternoon in sunny Orlando.

DRW

Thanks for an interesting post about the Ice Pellets. Thankfully I was not flying anywhere yesterday, as it sounds like it was a real mess everywhere in the NE and mid-atlantic region.

I was listening to JFK Tower for about 45 minutes yesterday evening while surfing FT - found an interesting site, www.liveatc.net. At about the time CO cancelled their ops at EWR, the reports coming in at JFK from inbound a/c were getting worse over time.

They were landing on 4R with reports of good breaking action. As the ice pellets started, pilots started reporting icing from 1,000 ft down to runway. When the tower would give a clearance, "AA 40 heavy, clear to land runway 4R. Breaking action reported good; beware of icing from 1,000 ft. Caution wake turbulance, following 777 heavy on 3 mile final"

Eventually pilots started to report icing from 7,000 ft downward, which was then relayed in ATC clearances, and it seems the weather went downhill from there.

Then the clearances changed to "Speedbird XXX, clear to land 4R. Winds xxx from xxx. Breaking action reported good, beware of icing below 7,000 ft. Caution wake turbulance, following A340 heavy."

They had a good burst of arrivals as the icing reports got worse with very few departures which were rolling out of 4L. The few departures they had rolling out of 4L were all overseas carriers. The only US carrier that appeared to be operating was AA with an arrival from LAX (AA 40) and they had an arrival or two from LHR come in along with Virgin and Speedbird (BA). One B6 flight (A320) did come in, but I was under the impression B6 cancelled everything at JFK.

It looked like DL must have cancelled or diverted all of their international traffic as I didn't see anything from DL come in or out during that 45 minute period I was listening -- and JFK is normally a busy gateway for DL. It sounds like CO got many of their international arrivals in at EWR, even with a stop at YYR on the 57's.

Not sure what happened after I turned it off, but it certainly sounded like conditions were deteriorating quickly. Not sure if they closed up shop or continued with limited operations.

Have a great trip down to MCO! I always enjoy your posts and the knowledge you share, doobierw! It's nice to have a 757/767 "driver" here - I've only "driven" the Cessna 152 and 172 in VFR only conditions, but am not active at the moment.

I checked the data on flightaware.com. There were flights departing JFK all night back to Europe. Some many hours late, like BA114 at 5am, and AF7 at 4am.

Personally, I'm surprised that CO threw in the towels for its international departures. I've seen them delayed till the morning hours for its European flights and still won't cancel. But they didn't get anything out after the Beijing and Tokyo flights yesterday.

Now, we'll see how long it'll take CO to recover. Jetblue basically canceled all flights Thursday night and yesterday, but they're now back up departing flights. CO was operating yesterday morning and tried not to cancel until late, but now is facing the consequence.

As for freezing rain and ice, I was once on an AC 340 at YYZ. The aircraft was covered in ice when we boarded. We went to de-ice, but when they finished de-icing the whole plane, we already timed out. So, we had to de-ice again. We were at the bay for over an hour.

Thanks as always for the insightful post doobier - this type of info is almost like a drug for us aviation geeks.

We have four levels of braking action: Good, Fair, Poor, and Nil. We can't operate with Nil.

Pilots call the tower with braking action reports and they can be very subjective. A 757 might feel they had 'Fair' landing conditions (757 has a great braking system) while the ERJ right behind them might feel they got a ride on the ice rink and report 'poor' or 'nil'. Once someone mutters the word 'Nil', the aircraft on approach will go-around or be required to divert, depending on their fuel state and how long it takes the airport to get rid of a 'nil' report.

Great info, thanks for the clear explanation.

Thanks for the interesting and comprehensive explanation.

Am in SFO and hope that flight ops are back to normal today ...