Cognitive limits, CFIT avoided and the TAP Prague case

By Captain Bassani - ATPL/B-727/DC-10/B-767 - Former Air Accident Inspector SIA PT. https://www.personalflyer.com.br - captbassani@gmail.com - Feb/2026

Image Perplexity

A CFIT “avoided by seconds”.

On 17 January 2026, TAP Air Portugal flight TP1240, an Airbus A320neo (CS‑TVG) operating from Lisbon to Prague, experienced what Czech authorities have described as one of the most serious safety events at Václav Havel Airport in recent decades.

During the ILS approach to runway 06, the aircraft (according to the data) descended below the published minimum safe altitude for the procedure, with a high rate of descent and increasing speed, reaching less than 1000ft above the terrain over hilly countryside west of Prague.

Preliminary data notified to European investigators state that the crew descended below the cleared altitude of 4000ft, reaching a minimum radio‑altimeter height of 968ft above ground before initiating a sharp climb. The TAWS (EGPWS) generated terrain‑proximity warnings and, almost simultaneously, approach control alerted the crew to the altitude deviation and instructed an immediate climb.

The aircraft then climbed to around 5850ft and carried out a second approach and landing without further irregularities.

The Czech investigation authority (UZPLN) classified the event as a “serious incident” and indicated that the aircraft was only “seconds away” from a CFIT (Controlled Flight Into Terrain ) scenario, with a fully controllable aircraft being flown toward terrain without full crew awareness of the impending impact.

TAP has confirmed it launched an internal investigation, is cooperating with Czech authorities, and temporarily removed the crew from duty, which is standard practice after serious incidents.

Operational context: approach, terrain and weather

The operational context around Prague explains why this event is so worrying. The ILS 06 approach from the western sector crosses uneven terrain with hills, obstacles and industrial structures, where sector and procedure minimum altitudes are in the order of 4000ft to ensure adequate terrain clearance. Descending significantly below that level, especially with a high rate of descent, rapidly places the aircraft at critical AGL heights in an area where terrain margins are small.

On the day of the incident, Czech and international media reported deteriorated weather conditions, with fog and reduced visibility during the approach to Prague. Under such conditions, crews depend heavily on correct automation management, strict adherence to published minimum altitudes and continuous cross‑checking between barometric altitude, radio‑altimeter and procedure constraints. Publicly reconstructed vertical profiles based on tracking data (such as FlightRadar24) show a sustained descent with increasing speed, consistent with the description of a “high rate of descent” prior to the recovery.​

Although no official cause has yet been published, several analysts have mentioned, as a working hypothesis, an inappropriate use of flight guidance/automation modes during descent and approach, a frequent pattern in CFIT precursor events. In many such cases, small mismatches between the crew’s mental model of what the automation is doing and the modes actually selected only become obvious when a TAWS alert or ATC intervention exposes the deviation.​

Cognitive limits and plan continuation bias

When a flight drifts toward a CFIT scenario, it is rarely due to a lack of basic flying skills; it is usually driven by cognitive overload, bias, and automation‑management issues under high workload. HRV (Heart Rate Variability) and EEG (Electroencephalography) based experiments in A320 simulators show that approach and landing concentrate peaks of mental workload, with degraded fine control, monitoring and decision‑making, while cruise tends to support physiological recovery.​ In these critical phases, two phenomena become particularly dangerous: the cognitive limit, the point at which the brain can no longer integrate all relevant cuesm, and plan continuation bias, the tendency to push on with the original plan despite mounting evidence that conditions have changed.

Under time pressure, worsening weather and possibly late vectors or tactical changes, it is very easy for a crew to stay locked into the idea that the approach remains viable even as the vertical profile is eroding terrain‑clearance margins.​

In Prague, the reported profile (descent below minimum altitude, increasing speed, TAWS warnings, urgent ATC call, late recovery, and eventual normal landing) fits a classic “CFIT averted” storyline in which the last link, TAWS plus ATC prevents an impact with the ground. For training, the key question is uncomfortable:

Without TAWS and an alert controller, how many times would the crew’s cognitive limit have been exceeded without anyone realizing it in time?

What simulator training must change

If we want the TP1240 event to trigger real learning, simulator programs must train the brain that runs the cockpit, not just a clean execution of published profiles. This means designing exercises that deliberately expose crews to workload saturation, plan continuation bias and automation errors, followed by debriefings centered on how pilots managed their own cognitive limits.​

Some practical elements operators should require from their training programs:​

• Build approach scenarios with late vectors, worsening weather, runway changes and minor technical issues where the only safe answer is to simplify the plan (go‑around, holding, diversion), not “make it work” within the minima.

• Use objective performance and workload indicators (reading mistakes, unstable trajectories, delayed responses to alerts) to show, in debrief, when the crew has gone beyond a healthy cognitive limit.

• Treat plan continuation and confirmation bias as internal threats within the TEM (Threat and Error Management) framework, with explicit mitigation strategies (tactical time‑outs, check‑and‑challenge, plan reset).​

• Explicitly assess and reinforce observable competencies in Workload Management, Automation Management and Situational Awareness, aligned with EBT/CBT (Evidence-Based Training/Competency-Based Training) frameworks rather than mere profile adherence.​

  
  

The uncomfortable takeaway from the Prague incident is that, until cognitive limits and bias become central design drivers in training, we will continue to rely too often on last‑minute TAWS alerts and vigilant controllers to avoid CFIT “by seconds”.​​

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Safe flights!

Captain Bassani

Sources

• Czech notification of serious incident TP1240 – descent below cleared 4 000 ft, minimum RALT 968 ft, climb to 5 850 ft, second approach and landing uneventful.​

• International coverage of TP1240 including public trajectory reconstructions and Czech authority statements about the aircraft being “seconds away” from an accident.​

• Prague (LKPR) AIP and ILS RWY 06 procedure/sector data, including minimum altitudes and terrain context west of the airport.

• “Training pilots for cognitive limits and bias: what operators must change in the simulator”, used here as the basis for the cognitive‑workload and bias discussion.​

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