737 Wing Anti-Ice Use Above FL350

This video explores the 737 wing anti-ice system, particularly its use above FL350, which the manual states may cause a bleed trip off.

The video will not focus on procedures, which after establishing aircraft control, could potentially lead to performing the bleed trip off, cabin altitude warning, or rapid depressurization checklists, instead we will take a look at the system itself, what could happen, and what you can do, if accumulating ice at high altitude.

The preferred method of using wing anti-ice in-flight is to de-ice (remove visible icing), so you need only select it when required. Alternatively you can use wing anti-ice to anti-ice (prevent ice formation) but would require it being on longer.

Indication of ice accumulation would include visible ice on the flight deck window frames, windshield center post, or on the windshield wiper arm.

If you find yourself in icing conditions above FL350 that necessitates the use of wing anti-ice, and its use results in a bleed trip off, consider requesting a different altitude (higher to clear weather) or FL350 or below based on system knowledge.

Why is using wing anti-ice a factor above FL350? At these higher altitudes with higher thrust settings, using wing anti-ice may cause the high stage valve to open, causing a bleed air trip off due to over temperature in the duct.

The video shows the wing anti-ice system and winter weather considerations.

Topics covered include: wing anti-ice system, winter flying.