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Holdover Time (HOT) Tables

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Category: Ground Operations Ground Operations
Content source: SKYbrary About SKYbrary
Content control: EUROCONTROL EUROCONTROL

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Description

Aircraft Ground De/Anti Icing Holdover Time (HOT) tables are approved by the SAE G-12 Committee are issued each year prior to the northern winter season.

These are then reviewed by AEA, FAA, and TC (Transport Canada) who are the main practical sources of HOT information and each issues their own version of the HOT Tables and associated support publications independently of each other and SAE. The generic changes from one season to the next are usually relatively few. However, in recent years, issues with residues from thickened fluids have been the main driver for the appearance of product-specific HOT tables, which are increasingly used by operators.

Other "official" sources sometimes publish HOT which are then left as "current" when they cease to be the latest versions. The effect of such out of date information being still accessible has resulted in many Operations Manuals being out of date on this critical safety subject.

In recent years, several companies have been developing systems that measure precipitation rate in real-time. These systems, referred to as liquid water equivalent systems (LWES), can be used by check-time determination systems (CTDS) and holdover time determination systems (HOTDS) to calculate more precise holdover times than can be obtained from the HOT Tables. They do this by using the weather data they collect as the input to the underlying assumptions employed in calculating the times in the HOT Tables.

Association of European Airlines (AEA)

  • The two regularly updated AEA Guides on the subject are:
    1. "Recommendations for De-Icing/Anti-Icing Aeroplanes on the Ground" (Edition 28 of this guide was published in July 2013) and
    2. "Recommendations and Background Information for De-Icing/Anti-Icing Aeroplanes on the Ground" (Edition 10 of this guide was published in August 2013)

Transport Canada (TC)

Federal Aviation Administration (FAA)

As a result of the development of LWES, CTDS and HOTDS, the FAA is making the regression coefficients and equations underlying the holdover time tables available to users:

Related Articles

Accident Reports

Accidents and Incidents resulting from airframe icing and problems with anti-icing fluids:

  • B762, Los Angeles USA, 2006 (FIRE GND AW) (On June 2, 2006, an American Airlines Boeing 767-200ER fitted GE CF6-80A engines experienced an uncontained failure of the high pressure turbine (HPT) stage 1 disc in the No. 1 engine during a high-power ground run carried out in designated run up area at Los Angeles for maintenance purposes during daylight normal visibility conditions. The three maintenance personnel on board the aircraft as well as two observers on the ground were not injured but both engines and the aircraft sustained substantial damage from the fuel-fed fire which occurred as an indirect result of the failure.)
  • RJ85, Helsinki Finland 2010, (AW GND LOC) (On 12 June 2010, a requested 22R runway inspection at Helsinki in normal daylight visibility carried out after a severe engine failure during the take off roll had led an Avro RJ85 being operated by Finnish Airline Blue1 on a scheduled passenger flight to Copenhagen to reject that take off at high speed. This inspection had not detected significant debris deposited on the runway during the sudden and severe engine failure. Two passenger aircraft, one being operated by Finnair to Dubrovnik, Croatia and the other being operated by Swedish airline TUIfly Nordic to Rhodes, Greece then departed the same runway before a re-inspection disclosed the debris and it was removed. Neither of the aircraft which used the runway prior to debris removal were subsequently found to have suffered any damage but both were advised of the situation en route.)
  • ATP, Jersey Channel Islands, 1998 (GND HF) (On 9 May 1998, a British Regional Airlines ATP was being pushed back for departure at Jersey in daylight whilst the engines were being started when an excessive engine power setting applied by the flight crew led to the failure of the towbar connection and then to one of the aircraft's carbon fibre propellers striking the tug. A non standard emergency evacuation followed. All aircraft occupants and ground crew were unnjured.)
  • Vehicle/PA31, Mackay SE Australia, 2008 (RI HF GND) (On 29 June 2012, a Piper PA31 taking off from runway 05 on a passenger charter flight just missed hitting an inspection vehicle which had entered the take off runway from an intersecting one contrary to ATC clearance. The overflying aircraft was estimated to have cleared the vehicle by approximately 20 feet and the pilot was unaware it had entered the active runway. The driver had been taking a mobile telephone call at the time and attributed the incursion to distraction. The breached clearance had been given and correctly read back approximately two minutes prior to the conflict occurring.)
  • B732, vicinity Washington National DC USA, 1982 (LOC HF WX GND) (On 13 January 1982, an Air Florida Boeing 737-200 took off in daylight from runway 36 at Washington National in moderate snow but then stalled before hitting a bridge and vehicles and continuing into the river below after just one minute of flight killing most of the occupants and some people on the ground. The accident was attributed entirely to a combination of the actions and inactions of the crew in relation to the prevailing adverse weather conditions and, crucially, to the failure to select engine anti ice on which led to over reading of actual engine thrust.)
  • … further results

warning.png"Ground de/anti icing" is not in the list of possible values (Taxiway collision, On gate collision, Aircraft / Aircraft conflict, Aircraft / Person conflict, Aircraft / Vehicle conflict, Aircraft / Object or Structure conflict, ATC clearance error, Ground de/anti icing ineffective, Jet Blast / Prop wash, Surface Friction, Towed aircraft involved, Aircraft Push Back, Incorrect Parking Position, Airbridge Positioning, Both objects moving, Wingtip clearance, Centreline obscured, Accepted ATC clearance not followed, Surface Lighting control, Hold Loading, Passenger Loading, Cargo Loading, Fuel Loading, Dangerous Goods, Engine Ground Running, Engine Powered Systems Test, No Flight Crew on Board, Charting Error, Failure to De/anti Ice) for this property.

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