Washington Plane Crash: How Faulty Altimeter Data Caused US Army Helicopter-Jet Collision That Killed 67

Washington Plane Crash report:  A deadly mid-air collision over the Potomac River near Washington, D.C., that killed 67 people in January 2025 was likely caused by a combination of faulty altitude readings aboard a US Army Black Hawk helicopter and critical lapses in air traffic control procedures. This was made known through a multi-day hearing held by the National Transportation Safety Board (NTSB) this week. This was revealed during a multi-day hearing conducted by the National Transportation Safety Board (NTSB) this week. The accident, which involved American Eagle flight 5342 and a military Black Hawk helicopter, is now being termed the deadliest US aviation disaster in over two decades. The inquiry results, which transpired over three days of testifying, reveal large inconsistencies in the helicopter's onboard gauges and breakdowns in the Federal Aviation Administration's (FAA) response to long-standing safety alerts. NTSB Chairperson Jennifer Homendy sharply criticised both the FAA and the Army for failing to deal with known hazards, describing the mistakes as "avoidable and systemic."

The NTSB revealed that the Sikorsky (a subsidiary of Lockheed Martin)-built UH-60 Black Hawk helicopter might have been lower than indicated by its gauges at the moment of collision. The plane's radar and barometric altimeters indicated altitude variations of 80 to 130 feet upon post-crash examination. “There is a possibility that what the crew saw was very different than what the true altitude was,” said Homendy. “A 100-foot difference is significant, especially in restricted, low-altitude airspace like the one near Reagan National Airport, where helicopters must stay below 200 feet.”

Testing on three identical helicopters showed that when the rotors were spinning and producing lift, the difference between instruments increased substantially. The radar altimeter, based on reflections from the earth, showed much lower readings compared to the barometric altimeter, which measured changes in pressure to calculate altitude in relation to sea level. Such a discrepancy might have led the crew to assume they were at a safe altitude, but actually, they had climbed into the flight pattern of the jet. On January 29, 2025, the Bombardier CRJ700 operated by American Eagle was on final approach to Ronald Reagan Washington National Airport after departing from Wichita, Kansas. At the same time, the US Army Black Hawk was engaged in a nighttime training mission, flying at what was believed to be 180–200 feet, well below the 300-foot altitude where the crash occurred. The crash occurred right over the Potomac River, and both aircraft were destroyed.

What Is an Altimeter?

An altimeter is an essential device on board every civilian and military aircraft that calculates an airplane's altitude, or the vertical distance above a base. Knowing an airplane's actual altitude is vital for flying safely, particularly in heavy traffic or controlled airspace such as that around Ronald Reagan Washington National Airport. There are two main types of altimeters typically used in aviation:

1. Barometric Altimeter (Pressure Altimeter)

This is the most usual altimeter type. Altitude is approximated using air pressure. Because atmospheric pressure is lower with altitude, the barometric altimeter determines how much above mean sea level the aircraft is flying by measuring the air pressure around it and comparing it with standard atmospheric data.
• How it works: The altimeter has aneroid capsules, thin, air-tight metal chambers that expand or shrink with changes in pressure. These motions are translated through linkages and gears to turn a dial or digital readout indicating altitude in feet or meters.
• Why adjustments are important: Because local weather conditions can influence air pressure at sea level, pilots have to adjust the altimeter by a setting called the altimeter setting (QNH or QFE), which air traffic control supplies on a regular basis.

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2. Radio Altimeter (Radar Altimeter)

A radio altimeter, on the other hand, indicates true altitude—that is, how high the aircraft is above ground or water immediately below. It achieves this by means of radio waves.
• How it works: The instrument transmits a radio signal directly down to the ground and computes the time it takes for the signal to reflect back. Because radio waves travel at light speed, the system is able to accurately measure the distance.
• Where it's used: Radio altimeters are generally used at lower elevations (below 2,500 feet), e.g., landing, hovering, or terrain-following missions—like the training operation of the Army Black Hawk over the Potomac River.

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Why the Altimeter Error Was So Critical in the Washington Crash

The NTSB inquiry into the collision at Washington uncovered an alarming inconsistency, the Black Hawk's instruments indicated it was at a safe altitude, but in fact, it was far higher—too high for the course it was following.

• Test findings: After-crash tests on three Black Hawk helicopters within the same Army battalion showed 80-to-130-foot discrepancies between radar and barometric altimeter readings. In actual flight, after rotor lift was established, the discrepancy grew large enough to produce a false altitude reading.

• Crash altitude mismatch: The highest allowed altitude for the helicopter's flight path along Reagan Airport was 200 feet. But the crash happened at around 300 feet, where it was in the direct line of travel of the incoming American Eagle passenger airplane.

• Operational risk: With so many civilian and military flights jostling each other in Washington's densely populated airspace, where each flight flies in narrow vertical corridors, even a 100-foot error can send two planes on a collision course. The margin for error is zero.

• Training conditions compounded the problem: The Black Hawk was on a night training flight wearing night vision goggles, so it was relying more on instruments than on visual references. This made the altimeter malfunction more dangerous, since pilots were basing their decisions on incorrect information.

Altimeters serve as the eyes of the cockpit, particularly during low-visibility conditions or complex airspace navigation. In the case of the January 2025 Washington plane crash, an altitude reading off by even a few dozen feet proved fatal. The tragedy highlights the importance of accurate instruments, timely testing, proactive safety communication, and above all, listening to repeated internal warnings before disaster strikes.