Controlled Flight Into Terrain (CFIT) happens when a pilot unintentionally flies an airworthy aircraft into the ground or water. So how can that possibly happen? It usually occurs when pilots get distracted or disoriented.

According to the FAA between 1979 and 1990, nearly 45% of all accidents resulted from CFIT. But it's not just a problem from 20 years ago, there have been several major CFIT accidents in just the last few years, including UPS Flight 1354, an A300 crash that happened just two years ago.

CFIT accidents aren't just limited to airliners either. CFIT is a common cause for GA accidents when pilots fly VFR into IMC.

So what exactly happens in a CFIT accident? It's usually a combination of events, so let's take a look at two major CFIT accidents: Eastern Flight 401, and Air New Zealand Flight 901.

Eastern Airlines Flight 401

Flight 401, a Lockheed L-1011, departed New York JFK airport for Miami International airport on December 29, 1972. As the L-1011 approached Miami at 11:32 pm, the pilots lowered the gear for landing. However, the nose gear position indicator light didn't illuminate. The pilots cycled the gear up and down, but the nose gear indicator light failed to illuminate again.

The pilots advised approach control that they needed to discontinue the landing, and the approach controller cleared them to enter a holding pattern at 2,000 feet over the Everglades west of Miami.

The aircraft entered a hold at 2,000 feet, and the captain instructed the first officer to engage the autopilot for the hold so they could troubleshoot the nose gear. The autopilot was selected to altitude hold mode, however, it's believed that the captain leaned on the control yoke, inadvertently switching autopilot modes from altitude hold to CWS (Control Wheel Steering), which maintains aircraft pitch.

The aircraft entered a very gradual descent, and after descending 250 feet, the aircraft made an altitude alert chime near the flight engineer's station. Unfortunately, the flight engineer was below deck in the avionics bay, trying to determine if the nose gear was down. The pilots didn't hear the chime, and the aircraft continued to descend.

After 50 seconds, the aircraft had lost approximately 1,000 feet, and was still descending. When the aircraft was just a few hundred feet above the ground, the first officer entered a turn into the autopilot, and noticed their altitude was not correct. He began an exchange with the captain, and they both were confused as to what was happening with the aircraft. Unfortunately, 10 seconds later, the jet crashed into the Everglades.

The investigation confirmed that there was nothing wrong with the nose gear, and the only problem on the aircraft was that both lightbulbs were burned out in the nose gear indicator. A $12 light bulb started the chain of events that lead to the crash, killing 101 of the 176 people on board.

Air New Zealand Flight 901

Flight 901 was a unique sightseeing flight from Auckland, New Zealand, to Antarctica, with a low pass over McMurdo Sound. The pilots on flight 901 had never flown the route before, but they were both highly experienced, and had been briefed on the flight plan.

However, what the pilots didn't know is that the flight plan coordinates that had been entered in the flight computer weren't the same as the flight plan they had briefed the day before. The coordinates entered into the computer took the plane almost directly over Mount Erebus, a 12,448 foot peak.

As the DC-10 approached Antarctica, the pilots descended through a cloud layer so the passengers could get a better view. However, the jet was well below the minimum safe altitude (MSA) of 6,000 feet, where they thought they were, and based on the cloud conditions. The MSA for their actual location was 16,000 feet, and the DC-10 was only at 1,500 feet MSL.

As the jet approached Mount Erebus, a cloud layer blended in with the snow-capped mountain, providing no contrast between the two. The pilots were unable to see the mountain directly in front of them, and they had no idea where they were until the ground proximity warning system (GPWS) sounded. The captain immediately requests go-around power, but six seconds later, the plane impacted the mountain, killing everyone on board.

The Takeaway

Both of these accidents could have been prevented. In the Eastern Airlines accident, the pilots over focused on the landing light, and didn't maintain situational awareness. The crew was also relatively new to the aircraft, and didn't fully understand what had happened to the autopilot system.

In the Air New Zealand flight, had the crew not descended through the cloud layer and below the MSA, they would have safely crossed over Mount Erebus, even though they were not in the location they thought.

But in both accidents, distraction and disorientation were the root cause. Take away those factors from both flights, and they most likely wouldn't have crashed.