On Jan 17th 2026, a TAP Air Portugal Airbus A320-200N, registration CS-TVG, descended far below its cleared altitude during approach to Prague, prompting air traffic control intervention and a subsequent serious incident investigation.
The aircraft, operating flight TP-1240 from Lisbon to Prague, was established on final approach to runway 06 approximately 17 nautical miles from the threshold. At the time, the jet had been maintaining 4,000 feet as cleared. However, instead of continuing level at that altitude, the aircraft entered a steep descent, dropping to about 2,600 feet mean sea level. ADS-B data, corrected for ambient pressure, indicated a minimum of approximately 2,425 feet MSL.
With ground elevation in the area at roughly 481 meters (1,577 feet MSL), the aircraft descended to close to 1,000 feet above ground level—well below the published minimum safe altitude of 3,600 feet MSL for that segment of the approach.
Shortly after the unexpected descent, the crew initiated a steep climb, reaching approximately 5,200 feet MSL. The aircraft then entered a left-hand 360-degree turn, descended back to 4,000 feet, and re-established itself on approach. The A320neo subsequently continued inbound at 4,000 feet and landed safely on runway 06 about 11 minutes after the premature descent event.
Despite the earlier deviation, the aircraft later departed Prague on its scheduled return flight without reported delay.
On Feb 12th 2026, the Czech Republic’s Ústav pro odborné zjišťování příčin leteckých nehod (UZPLN) confirmed that air traffic control had detected a violation of the cleared 4,000-foot altitude. According to the authority, the flight crew responded to controller instructions following the deviation. The occurrence has been classified as a serious incident and is now under formal investigation.
Serious incidents of this nature draw heightened scrutiny because controlled flight toward terrain, even if corrected in time, can erode established safety margins. Investigators will likely examine cockpit workload, automation management, situational awareness, and any possible misinterpretation of approach procedures or altitude constraints as they work to determine how the aircraft came to descend nearly 1,400 feet below its assigned level.
