Customs Training Loss of Control While Climbing Away from a Quick Stop

Customs Training LOC-I While Climbing Away from a Quick Stop (CBP Airbus AS350B2 N841BP)

On 13 May 2021 Airbus AS350B2 N841BP of US Customs and Border Protection (CBP) Air and Marine Operations (AMO) was destroyed in a training Loss of Control – Inflight (LOC-I) accident at Yukon, Oklahoma. Both pilots escaped injury but the aircraft was consumed by a post crash fire.

Wreckage after Post-Crash Fire of Customs and Border Protection (CBP) Airbus AS350B2 after Loss of Control – Inflight During Training (Credit: Airbus Helicopters via NTSB)

The Accident Flight

According to the US National Transportation Safety Board (NTSB), who issued their safety investigation report 19 January 2023 the pilot under instruction had been enrolled on CBP’s Initial Pilot Certification course for the AS350B2 at the CBP National Air Training Center (NATC) in Oklahoma City.  The student was aged 45, held a CPL and had 1,200 hours total, 620 hours on type.  The instructor was 40 and had 6,000 hours total, 1,000 on type.

The instructor reported for duty at c11:30 Local Time and started preparing with the student at 12:30 for 2 flights.  The aircraft departed at 14:45.  The pilot under instruction was in the right hand seat,

The flight departed the Will Rogers International Airport (KOKC) and proceeded to the Clarence Page Municipal Airport (KRCE) to conduct training maneuvers.

After arrival at KRCE, the flight crew conducted several approaches to the airport including confined area and pinnacle approaches.

They then conducted several simulated emergencies, each of which required the helicopter’s hydraulic system to be turned off and then turned back on at the conclusion of the procedure.

Readers should note that:

The hydraulic system was turned off and on using the hydraulic cut-off switch, an unguarded push-button switch mounted on the end of the pilot’s collective stick.


…the flight crew proceeded to conduct a series of “quick stops.” After the third quick stop, the pilot heard a radio call indicating an airplane was on final approach to land on the runway they were using, and the flight instructor indicated that they would clear the runway. The pilot [under instruction] added that he completed a final quick stop and immediately entered a climbing left turn.

At this point the pilot under instruction noticed the helicopter was yawing to the left.  He was unable to correct that with a pedal input.

When the pilot [under instruction] adjusted his grip on the collective, he felt the hydraulic cut-off button with his thumb as he prepared to reduce collective. As he tightened his grip on the collective, “the hydraulics came offline aggravating the left yaw into a hard left spin.”

The controls were stiff, and the flight instructor told him to turn the hydraulics back on.

The pilot “intentionally pressed the [hydraulic cut-off] button but felt no effect.” He pressed the button a second time, but the hydraulic light on the caution warning panel remained illuminated, so he pressed the button a third time.

However the flight instructor stated that during the last quick stop “the helicopter slowed normally but then started a left yaw about 25 ft above ground level”.  As the helicopter yawed to c 30° left the instructor “pushed forward on the cyclic to gain airspeed”.  Its not clear from the NTSB report if he verbalised that intervention.

He stated that “as the aircraft was recovering, the control loads instantly became excessive” and “noticed the hydraulic light on the caution warning panel was illuminated”.  It was only at that point according to the instructor’s statement said (emphasis in original):


According to feedback from CBP to NTSB added to the draft report:

…the pilot [under instruction] did not relinquish control.

According to the NTSB report…

The flight instructor attempted to regain control of the helicopter but was unable to overcome the high control loads.

The helicopter continued to spin, impacted the ground in a nose-down attitude, rolled over, and came to rest on its right side.

Ground Scars and Wreckage of Customs and Border Protection (CBP) Airbus AS350B2 after Loss of Control – Inflight During Training (Credit: Airbus Helicopters via NTSB)

Both pilots rapidly egressed as a post-impact fire consumed most of the helicopter.

Safety Investigation

CBP conducted their own investigation report.  Though this was not released into the public docket.

Examination of the helicopter was limited by the postimpact fire; however, no preimpact abnormalities were identified with helicopter’s airframe and engine.

The NTSB then explain that CBP reported that “the agency’s selection process for the Air Interdiction Agent Program failed to properly identify that the pilot was not qualified for the program”.

The NTSB then conclude:

Because the pilot did not have the qualifications and experience required for the Air Interdiction Agent Program, he did not have the prerequisite skill necessary to critically assess the situation given by the flight instructor.

This resulted in the pilot applying improper corrective actions and failing to relinquish control of the helicopter to the flight instructor when directed, which contributed the accident.

This is an odd conclusion!  The pilot had a CPL, 1,200 hours total, 620 hours on type and the training exercise was a fairly conventional basic type training. This conclusion appears entirely based on the unreleased CBP internal report.

The AIS flying training at NATC only follows a 15-week Air and Marine Basic Training Program (AMBTP) at the Air and Marine Operations Academy (AMOA), located at the Federal Law Enforcement Training Center (FLETC) in Glynco near Brunswick, Georgia.  If the individual “did not have the qualifications and experience required” then it is remarkable that it was only apparent after an accident in the post-AMBTP flying.

NTSB Probable Cause

The pilot receiving instruction’s untimely and unidentified inadvertent activation of the hydraulic cut-off switch, which turned off the hydraulic system while the helicopter was at slow airspeed followed by a rapid power increase, which resulted in a loss of control.

Contributing was the pilot’s failure to relinquish control of the helicopter to the flight instructor when directed.

Our Observations

Disappointingly neither were any safety recommendations are made nor any safety actions reported by the operator.  There was also no discussion on CBP’s procedures for transferring control between pilots or indeed of the syllabus of training, quality of instruction and general management of the AIA Program.

NTSB did consider making a recommendation to CBP to fit a crash resistant fuel system to their AS350s. The NTSB mention this accident that attracted considerable attention: Crashworthiness and a Fiery Frisco US HEMS Accident which we wrote about first in late July 2015.

In light of their low level, high risk law enforcement role in remote border regions this would be an eminently sensible proposal.  NTSB however decided not to because “we’d have to address all AS 350 helicopters operating in the US” but in an e-mail to CBP stated they were:

…willing to brief your leadership on the issue and our findings following accidents involving fuel tank fires to hopefully convince them to go that route.

CBP responded:

We are interested in the presentation that you proposed, but we will have to wait on that for some time. There are external investigations that are being conducted into this event, and we need for those to conclude prior to any presentation.

Its not clear what these other investigations were that delayed a CRFS safety briefing were.

UPDATE 19 November 2023: CBP hid details about near-fatal helicopter crash at secret flight school: whistleblower

Safety Resources

The European Safety Promotion Network Rotorcraft (ESPN-R) has a helicopter safety discussion group on LinkedIn.

Aerossurance’s new case studies will shortly include an offshore helicopter training related accident to learn from.

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