APS Holdover Times App

Accessing and calculating holdover times has never been easier. 

Holdover Times
Quicker and safer holdover time calculations easily accessible in an iOS app.
Trusted Worldwide
Ten major airlines and over 35,000 pilots in 30 countries now use the APS Holdover Times App.
Extensive experience and exhaustive data verification warranty the accuracy of every holdover time provided.

Two Ways to Obtain Holdover Times

HOT Calculator

Calculate the holdover time for current conditions by entering the applicable weather and fluid information. The appropriate holdover time will be provided, along with all related notes and cautions and the applicable holdover time table PDF.

Use the “HOT Clock” and related graphics to keep track of the status of your holdover time. The status bar fills in as the holdover time is used up and the traffic light alerts you to your status within the holdover time range:

  • Green light: below lowest HOT in range
  • Yellow light: between lowest and highest HOTs in range
  • Red light: longest HOT in range exceeded

The HOT Calculator incorporates lowest operational use temperatures (LOUTs) for Type II, III and IV fluids for FAA and Transport Canada and provides an alert when the air temperature entered is below the LOUT.


PDF Viewer

Use the PDF viewer to access the Transport Canada and FAA holdover time documents electronically without an internet connection.

The PDF Viewer divides the holdover time documents into individual PDF files which are sorted into categories for easy navigation and viewing. All tables and guidance contained in the holdover time guidance documents are accessible using the PDF Viewer.

Related guidance documents for each authority are also provided and easily accessible.


Customize our App

We create customized versions of our app to meet the specific requirements of individual airlines and operators. Customization can include inclusion or exclusion of specific authorities, fluids, holdover times, guidance materials, and app features.

We can also incorporate your company’s guidance materials – either as PDFs or integrated into app functionality.

Learn how a customized app can help your business operate more safely and efficiently in winter conditions.

Frequently Asked Questions (FAQs)

If your question isn’t answered here, please contact us at apps@apsaviation.ca.



Do I need an internet connection to use the app?

No internet connection is required to use this app as the app stores all needed data on your device. It is recommended you connect your device to the internet periodically to check for app updates.

Is this app available for Android or Windows-based devices?

This app is currently only available for iOS-based devices. Developing Android and/or Windows-based versions is something being strongly considered for future, should market demand increase.

Why do I have to purchase a new app every winter?

We create a new app each year to publish the latest HOT information authorities publish for each winter. We do it this way rather than releasing an update as we need to cover the costs of incorporating the new data. This includes updating the very large database and the several hundred PDFs that power the app. We also need to check that every single number provided by the app (plus the associated notes, cautions and PDFs) is correct. This is not only critical for safety, but is also a requirement of the related Transport Canada Advisory Circular - AC 700-030. Charging annually for our app allows us to continue supporting the app each year and ensures our app, unlike others on the market, has complete and fully accurate data.

Do you offer training?

Holdover Times is an easy to use, intuitive app which requires minimal training. We offer a How to Use document within the app which guides users through the functionality of the app. Customized training modules are available for customized apps.



What qualifies APS Aviation to create this app?

We are the world’s leading experts on de/anti-icing fluid holdover times. We have been conducting research with de/anti-icing fluids since the early 1990s and are the only company in the world to conduct official holdover time testing; it is our research and analysis which determines the data that populates the holdover time tables. We also draft and manage the Transport Canada and U.S. Federal Aviation Administration (FAA) Holdover Time documents. We know HOT data better than anyone else and are uniquely qualified to provide this information in an app.

Has the app been certified / approved by authorities?

Neither Transport Canada nor the FAA certifies or approves holdover time apps. However, they do have (different) processes in place to authorize their use. Operators in both jurisdictions have gone through these processes and are currently authorized to use our app. Contact us for more information and support.

How can I be sure the HOT Calculator will return accurate information?

APS undertakes an extensive process to verify all data in the app. This process includes a manual verification of every possible combination of parameters used by the HOT calculator to verify the correct holdover time, notes and cautions are provided for those specific parameters. The verification process is documented both electronically and in hard copy and can be made available upon request by pertinent authorities.

How do I know the information in the app has not expired?

The authorities who publish the data included in this app do not include expiry dates when they publish their data. Therefore, the data has no official expiry date. The data only becomes obsolete when a newer version is published. Newer versions are published annually, for each winter season, typically in late summer/ early fall. We create and publish a new app every fall to provide the new winters published information. If an update to a publication is released mid-season, we update the current winters app accordingly and release a free update. To ensure a previous winters app (and its obsolete data) is not used, we have programmed our app to stop working on October 15th of the year following its applicable winter.



Why is the HOT Calculator giving me the message "No Holdover Times Exist"?

Holdover times do not exist in all conditions. When you get this message, a reason will be provided. For example: you've chosen a precipitation type for which authorities do not provide holdover times (i.e. heavy snow, hail) or have used a fluid that can't be used in the conditions selected (i.e. Type I fluid in Ice Pellets).

Why am I not getting alerts from the HOT Calculator?

If you are not getting alerts from the HOT Calculator, check your device settings. Open the settings app on your iPad/iPhone, scroll down on the left menu, and tap "2018-19 HOTs". On the right side of the screen, tap "Notifications". Ensure that "Allow Notifications" is on. We recommend enabling the "sounds", "badge app icon" and "show on lock screen" options. In iOS 11 we recommend enabling "Show as Banners" and using the "Persistent" display. In iOS 10 we recommend choosing "Alerts" for the "alert style when unlocked". These settings will result in alerts that are more visible and require a tap to dismiss.

How are Lowest Operational Use Temperatures (LOUTs) incorporated into the HOT Calculator?

The LOUTs published by Transport Canada and the FAA for Type II, Ill and IV fluids are incorporated into the HOT Calculator for these authorities. When one of these fluids is selected and the temperature selected is below the fluid's LOUT, no holdover time will be provided. If LOUTs are not available, a caution note is provided accordingly.

Join our Mailing list

Want to be informed when new apps and app updates are released? Send an email to apps@apsaviation.ca with the subject "Subscribe to APS App Mailing List". We'll add you to our mailing list and you'll be informed each time we release an update or a new app.

About Us

APS Aviation Inc. is an aviation engineering firm based in Montreal, Canada specializing in winter operations. We have been responsible for developing and managing the holdover time table data on behalf of Transport Canada and the FAA for the last two decades. We are a member of the RHEA Group.