According to a report by French authorities, an aeroplane carrying 172 passengers came within 6 feet (1.8 metres) of crashing while making its approach to Paris Charles de Gaulle (CDG). On May 23, 2022, at at 11:40 UTC, the Airbus A320, with the registration 9H-EMU and operated by wet lease expert Air hub, was coming in to land at CDG on a trip from Stockholm Arlanda when the near-collision occurred because of an improper altimeter setting.

The approach was flown 280 feet lower than it should have been because the controller repeatedly gave the crew the wrong QNH setting, 1011 instead of 1001, and the crew failed to notice the error. The Minimum Safe Altitude Warning (MSAW) was triggered on both approaches during this serious incident, and the controllers failed to use the prescribed MSAW phraseology. The report noted that the crew was not provided the QNH or any instructions to verify their altitude.

For Air hub, the BEA recommends that crews are made aware of the importance of the correct QNH setting for such RNP approaches and implement a procedure to cross-check QNH information with another source.

First approach – Horizontal flight path

The flight, which was being flown on behalf of Norwegian Air Shuttle, was making an LNAV/VNAV minimum RNP approach to runway 27 at CDG. Because the aircraft will get its altitude information from the barometric altitude systems, this style of approach depends on pilots using the proper QNH setting.

According to the preliminary report from the BEA, air traffic controllers received a ground Minimum Safe Altitude Warning at 11:41:32, when the aircraft was at an indicated altitude of 617 ft on the correct QNH of 1001, or 200 feet above the ground according to the radio altimeter, at 1.53 nautical miles from the runway threshold. With a QNH setting of 1011, the crew would have seen an indicated altitude of 891 ft. CDG is 392 ft above sea level.

At 1.2 nautical miles from the runway, nine seconds later, the crew passed the decision altitude of 802 feet in accordance with the inaccurate 1011 QNH setting. The crew decided to turn around since they could not see the runway. However, the aircraft was 122 feet above the ground when the QNH was adjusted to the proper altitude of 1001, which was 537 feet.

The autopilot was removed and the captain pitched the aircraft up at 11:41:47, 15 seconds after ATC received the alert and during the controller’s call to the aircraft. The aircraft’s lowest point above the earth, measured by the radio altimeter at just 6 ft, was reached three seconds later and when it was still 0.8 miles from the runway.

Second approach

On the second approach for landing, the faulty QNH setting was not corrected, and the aircraft was again 280 ft lower than it should have been. Another MSAW was generated when the aircraft was 3.1 nm from the runway at an indicated altitude of 1,403 ft on QNH 1011 (but 1,131 ft QNH 1001, 842 ft per the radio altimeter).

When called by the controller, the crew said they did not understand why the message had been received but that they were visual with the runway. However, runway PAPI lights indicated to the crew that they were lower than they should be, so they corrected the approach and landed safely.

Courtesy : BEA