Sunday, May 29, 2011

Blue Angels Report

Those who pay attention to military aviation news reports know that last weekend at Lynchburg VA the Blue Angels had a problem during the Sunday show. The fallout was first a grounding of the team for a procedural review and safety stand-down. When things go wrong that is not uncommon. The role of aerial demonstration teams is strictly to demonstrate skill, performance, training and the ability to operate safely. Accidents occasionally happen, but they are blessedly rare as a result of very strict standards.

A few days later, the leader of the Blues announced voluntary resignation from the position although there was no description in his statement regarding what precisely was the issue.

Here is a video which shows what happened. The shows were done on Saturday and Sunday last weekend. The first half of the video is from the Saturday show. The second half is the Sunday show. Notice that the narration is exactly the same. The outcome, however, is different:

The minimum altitude for the recovery is 500 feet AGL. On Sunday you see the wingmen realize they have breached the minimum and breaking off of the formation. The slot man may or may not be aware of the altitude since his formation references are largely above his head and not level with the HUD display of altitude or sink rate. He maintains position and best estimates are that he bottoms out around 120 feet. Responsibility for that minimum altitude rests entirely with the formation leader.

Those who have been around for awhile will inevitably flash back to a Thunderbirds accident in 1982 during team transition at Thunderbird Lake north of Nellis. They were flying the T-38 at that time and the new leader, Maj. Norm Lowry, was a friend of mine from my days at Torrejon in the 401st TFW. Misjudging the altitude down the back side of a loop resulted in an accident in which all four aircraft in the diamond were lost.

We've come a long way since then.


chris parker said...

Looks like the leader flew down to the base height rather than misjudged the pull-out. They all looked comfortable on the way down.

juvat said...

I thought the Thunderbird accident was found to have been a flight control malfunction, trim motor or something like that.

Ed Rasimus said...


The accident board initially called "pilot error" then Gen Creech called them back and explained that "Thunderbirds don't make pilot errors, find something else". They reconvened and wrote it up as a malfunction of the "shock absorber" in the pitch control system.

We had 160 AT-38s at Holloman at that time. Okie Page was pilot officer on the board and Ron Somebody-or-other was board president. We also had the maintenance member of the board (it was a TAC accident and we were the greatest pool of Talon operators in TAC).

Nobody could really find a single reference to a "shock absorber" in the slab control system but they were all "inspected" and cleared for flight. No pictures or descriptions in the -1 or maintenance manuals either.

Recall that trim was handled by stick positioning, not moving the control surfaces. The stick was adjusted to command the desired trim positions. Control feel never changed and max stick force never exceeded five pounds total for full displacement.

I did encounter (regularly) something I called a slab stall on the Talon. If you commanded too much slab at low airspeed you could actually get it to exceed critical AOA and somehow never get any bite as airspeed built so that your nose didn't want to move. A simple release of pressure momentarily would re-establish control and responsiveness. Worked just like any stall recovery.

Hippo said...

I was stationed at HQ/TAC when this accident happened. The word on the street was that GEN Creech directed the accident board to find something wrong with the lead airplane because he feared that a "pilot error" finding would spell at the end of the T'Birds.

Dudley Henriques said...

The "Diamond Crash"
As Ed knows, I did some tests in the Talon on slab stall and it is indeed true that through the float under 150kts inverted you can input pitch to the slab tail on the 38 that can result in a change in positive nose rate. This could or might not have been a factor for TB1 as Lowery took the team through the float at Indian Springs.
Unfortunately the "investigation" thanks to the Creech bounce, left more questions than answers. I know Patterakis wasn't at all convinced that Lowery had a slab actuator issue I share Chris' view.
Al King's tape of the crash impact has never been found to my knowledge after it's acquisition by TAC.
My opinion leans heavily, based on what I know personally about the scenario involved with the line abreast loop that day is that Lowery, a fine fighter pilot and a smooth lead, very well might have simply missed his high energy gate parameters and took the team through the high gate too low and very possibly too fast. That combination jives perfectly with testimony that the backside formation looked fast and normal. It also computes to a higher TAS and wider turn radius through the backside recovery.
It's also felt by many that had the formation been in the Diamond and not line abreast, there could have been a "go exploded call" based on the visual cues available to the wings and especially the slot, (yes, good display formation pilots actually CAN take a peek in the diamond display formation based on where in the maneuver they are and their experience in the position) Line abreast is a whole different story as far as visual cues vs painting your position is concerned. You're REALLY trusting lead in line abreast.
The Thunderbird Diamond Crash will always be the subject of much controversy in the display community. My personal opinion is that the final answers died with Bill Creech.
Dudley Henriques