Holdover time (HOT) guidelines for de-icing and anti-icing aircraft

The holdover time (HOT) guidelines provide estimates of how long aircraft anti-icing fluids will be effective. They help aircraft flight crews make decisions when de-icing and anti-icing an aircraft on the ground.

On this page

• Current HOT guidelines
• Current degree-specific holdover time (DSHOT) database
• About the HOT guidelines
• Archived HOT guidelines
• Regression information documents
• Contact us
• Related links

Current HOT guidelines

Request a copy of the Winter 2022-2023 Holdover Time (HOT) Guidelines: Original issue, August 3, 2022 - Revision 2.0: August 31, 2022

To receive the guidelines, you will have to provide a valid e-mail address when prompted.

Request a copy of the HOT Guidelines: Revision 2.0 , August 31, 2022

About the HOT guidelines

We update and reissue HOT guidelines every year. Sometimes we publish a revision in the same year.

These guidelines contain tables with explanatory notes. These tables provide aircraft flight crews with safe holdover times given the following criteria:

• Air temperature
• Type of precipitation
• Rate of precipitation
• Type of de-icing or anti-icing fluid

Normally, aircraft should not take off after the holdover time has expired. Aircraft may take off only after either:

• a pre-take-off contamination inspection is done
• the aircraft is de-iced or anti-iced again

Refer to the Guidelines for Aircraft Ground-Icing Operations (TP 14052) when using the HOT guidelines.

Archived HOT guidelines

The following guidelines are no longer used. We provide them for informational purposes only. If you require an alternative format, please contact us.

• 2022-2023

  Request a copy of archived HOT guidelines—Revision 1.0, August 11, 2022

  To receive the archived HOT guidelines, you will have to provide a valid e-mail address when prompted.

  Request a copy of archived HOT guidelines—Revision 1.0, August 11, 2022

• 2021-2022

  Request a copy of archived HOT guidelines—Original issue, August 4, 2021

  To receive the archived HOT guidelines, you will have to provide a valid e-mail address when prompted.

  Request a copy of archived HOT guidelines—Original issue, August 4, 2021

• 2020-2021

  Archived—Original issue, August 2020 (PDF, 4.03 Mb)

• 2019-2020

  Archived—Original issue, August 2019 (PDF, 6.31 Mb)

• 2018-2019

  Archived—Original issue, August 2018 (PDF, 2.15 Mb)

• 2017-2018

  Archived—Revision 1.0, October 2017 (PDF, 4.54 Mb)
  Archived—Original issue, August 2017 (PDF, 3.84 Mb)

• 2016-2017

  Archived—Original issue, August 2016 (PDF, 2.62 Mb)

• 2015-2016

  Archived—Revision 1.0, December 2015 (PDF, 1.46 Mb)
  Archived—Original issue, July 2015 (PDF, 1.71 Mb)

• 2014-2015

  Archived—Revision 1.0, August 2014 (PDF, 2.06 Mb)
  Archived—Original issue, August 2014 (PDF, 2.98 Mb)

• 2013-2014

  Archived—Original issue, August 2013 (PDF, 1.12 Mb)

• Before 2013-2014

  Archived—Revision 1.0, July 2012 (PDF, 1.08 Mb)
  Archived—Original issue, July 2012 (PDF, 851 Kb)

  Archived—Original issue, July 2011 (PDF, 790 Kb)

  Archived—Original issue, July 2010 (PDF, 409 Kb)

  Archived—Original issue, July 2009 (PDF, 328 Kb)

  Archived—Original issue, July 2008 (PDF, 316 Kb)

  Archived—Revision 1.0, October 2007 (PDF, 405 Kb)
  Archived—Original Issue, July 2007 (PDF, 288 Kb)

  Archived—Original issue, July 2006 (PDF, 257 Kb)

  Archived—Original issue, July 2005 (PDF, 352 Kb)

  Archived—Revision 1.0, December 2004 (PDF, 248 Kb)
  Archived—Original issue, July 2004 (PDF, 185 Kb)

  Archived—Revision 1.0, December 2003 (PDF, 247 Kb)
  Archived—Original issue, July 2003 (PDF, 180 Kb)

  Archived—Original issue, September 2002 (PDF, 1.25 Mb)

  Archived—Original issue, November 2001 (PDF, 1.38 Mb)

  Archived—Original issue, October 2000 (PDF, 881 Kb)

  Archived—Original issue, November 1999 (PDF, 1.26 Mb)

  Archived—Original issue, October 1998 (PDF, 1.18 Mb)

  Archived—Original issue, September 1997 (PDF, 998 Kb)

  Archived—Original issue, September 1996 (PDF, 686 Kb)

  Archived—Original issue, July 1995 (PDF, 716 Kb)

  Archived—Original issue, October 1994 (PDF, 431 Kb)

  Archived—Original issue, October 1993 (PDF, 975 Kb)

  Archived—Original issue, November 1992 (PDF, 1.98 Mb)

  Archived—Original issue, November 1991 (PDF, 691 Kb)

  Archived—Original issue, September 1990 (PDF, 901 Kb)

Regression information documents

To calculate more precise holdover times than those presented in the HOT guidelines, several companies manufacture and use HOT determination systems (HOTDS) to measure real-time temperature, precipitation type and precipitation rate. HOTDS use:

• weather data they collect
• regression information we provide

Request a Copy of the Winter 2022-2023 Holdover Time (HOT) Regression Information Document: Original issue, August 3, 2022

Request a copy of the Regression Information Document

Contact us

Civil Aviation Communications Centre

Related links

• Guidelines for Aircraft Ground-Icing Operations (TP 14052)
• Aircraft icing training courses and resources (at NASA)
• When in Doubt ... Small and Large Aircraft - Aircraft Critical Surface Contamination Training for Aircrew and Groundcrew (TP 10643)
• Advisory Circular (AC) 700-030 Electronic Holdover Time (eHOT) Applications
• Advisory Circular (AC) 700-061 Degree-Specific Holdover Degree-Specific Holdover Times
• Advisory Circular (AC) 602-001 Operational Use of Remote On-Ground Ice Detection Systems (ROGIDS) for Post De-icing Applications