Figure: Hot tower from Hurricane Bonnie, 1998, from NASA visualization studio via Wikimedia Commons.

Eddie Sez:

There have been quite a few instances where aircraft had been flying along happily at altitude over the ocean when the outside air temperature suddenly rose thirty degrees or so and the aircraft mushed out of the sky. It has been reported by multiple Gulfstreams, usually GIV's, Boeings, and other aircraft. The phenomenon has been called "Hot Towers."

Gulfstream did a very good study about the problem that noted Hot Towers are real, but they were not related to the temperature rise issue experienced by these aircraft. The circulated a presentation that had all the right facts, but an unfortunate subtitle: "Hot Towers or Not." See: Ice Crystal Icing & Hot Towers. A careful read of the presentation leads you to the right conclusion: the encounters were a result of TAT probe icing, not a Hot Tower. But I continue to meet pilots from Gulfstream that claim Hot Towers caused an actual temperature rise.

Is this a problem? Probably not. But I think a better understanding about what a Hot Tower is and what is causing the problem will help you if you ever encounter the mysterious temperature rise.

What follows comes from the references shown below. Where I think it helpful, I've added my own comments in blue.


What is a Hot Tower?

[NASA Goddard]

[Gulfstream Hot Towers Presentation]

So Hot Towers are real, but you need to be in a tall cumulonimbus cloud, probably a hurricane, to experience one. All of the reported encounters by pilots, however, were in the clear. So what did all these pilots experience?


Example Reported Encounters

GIV "Encounter"

[Gulfstream Hot Towers Presentation]

GIV Second "Encounter"

[Gulfstream Hot Towers Presentation]

GV "Encounter"

[Gulfstream Hot Towers Presentation]


Common Trends in Reported Encounters

[Gulfstream Hot Towers Presentation]


The Real Cause: Ice Crystal Icing

[Gulfstream Hot Towers Presentation]

Gulfstream placed their focus on the Total Temperature Sensors


Gulfstream Total Temp Probe (Goodrich)

[Gulfstream Hot Towers Presentation]

There wasn't enough data to come to a firm conclusion so the Gulfstream study leaves you wondering. The preponderance of evidence, however, leads me to conclude the temperature rise was due to TAT probe icing, not a Hot Tower. There are no corrective actions specified by Gulfstream and I haven't heard of any from other aircraft manufacturers. So what can you do?

There have been no encounters of this by Planeview aircraft.


References

A "Hot Tower" Above the Eye Can Make Hurricanes Stronger, NASA Goddard, January 12, 2004

Ice Crystal Icing & Hot Towers, Gulfstream Product Support, John Salamankis, undated.

Wikimedia Commons, Public Domain Artwork