Decoding - FINAL INVESTIGATION REPORT OF SERIOUS INCIDENT TO M/S VISTARA AIRBUS A320 AIRCRAFT VT-TNH ON 15TH JULY 2019
On July 15, 2019, Vistara Flight UK944, operating an Airbus A320 (VT-TNH) from Mumbai to Delhi, declared a critical fuel emergency and diverted to Lucknow. With just 348 kilograms of fuel remaining, the aircraft landed under "Mayday Fuel" status—narrowly avoiding a major aviation disaster. This report, based on the official DGCA-AAIB investigation, decodes the sequence of operational missteps, weather challenges, and decision-making under pressure that defined this serious incident.
Timeline of Key Events (All Times in IST)
- 14:57 – Engine start at Mumbai with 8,500 kg fuel onboard
- 15:18 – Aircraft takes off from Mumbai
- 15:40 – IOCC updates Delhi weather (low visibility, thunderstorms)
- 15:45 – TAF confirms deteriorating weather at Delhi
- 15:57 – Flight crew discusses diversion options
- 16:57 – 40 NM from Delhi; ATC vectors aircraft for ILS Runway 29
- 17:20 – Go-around due to strong tailwind on final approach
- 17:25 – Crew diverts to Lucknow; Fuel on board: ~3.0 tons
- 18:00 – Weather worsens at Lucknow, RVR drops below minima
- 18:12 – Crew declares “Minimum Fuel”
- 18:16 – Approach aborted due to poor visibility (RVR < 300m)
- 18:24 – “Mayday Fuel” declared
- 18:27 – Clearance obtained to divert to Prayagraj
- 18:48 – Final landing at Lucknow with 348 kg of fuel
Flight Background
Vistara UK944 departed Mumbai with 155 passengers and 7 crew members. The initial alternate airports listed were:
- Transit Briefing Sheet: Ahmedabad (VAAH) and Lucknow (VILK)
- Operational Flight Plan (OFP): Lucknow (VILK) and Jaipur (VIJP)
The inconsistency in planning created immediate confusion. Severe weather at Delhi forced the aircraft into a holding pattern, burning through its extra fuel. A go-around was executed after a dangerous tailwind shift on final approach.
With fuel dropping quickly, the crew chose Lucknow over Jaipur despite Jaipur offering better weather and shorter distance. After a second aborted landing due to poor visibility, the crew declared a “Mayday Fuel” emergency and explored diversions to Kanpur and Prayagraj.
Pilot and Aircraft Information
Captain (Pilot Flying)
- Age: 30
- License: ATPL
- Total Hours: 8,550
- Aircraft Type (A320): 8,278 hrs
- Last 24 Hours: 5 hrs 12 min
First Officer (Pilot Monitoring)
- Age: 29
- License: CPL
- Total Hours: 1,600
- Aircraft Type (A320): 398 hrs
- Last 24 Hours: 5 hrs 12 min
Aircraft Details
- Type: Airbus A320-251N
- Registration: VT-TNH
- Year of Manufacture: 2018
- Engines: CFM LEAP 1A
- Maximum Takeoff Weight: 73,500 kg
- Max Usable Fuel: 18,623 kg
- Owner: ARCU Aircraft Leasing Ltd
Fuel Statistics
| Flight Phase | Fuel On Board |
|---|---|
| Takeoff (Mumbai) | 8,215 kg |
| After Delhi Go-Around | ~3,400 kg |
| Declared Minimum Fuel | ~1,100 kg |
| Declared Mayday Fuel | ~500 kg |
| Landing at Lucknow | 348 kg |
Analysis
Key Observations
- Inconsistent Alternate Planning: Crew received conflicting data on alternate airports.
- Company Preference Bias: Crew prioritized “Suitable Alternate” (Lucknow) over “Acceptable Alternate” (Jaipur), despite weather evidence.
- Dispatch Failure: No timely updates or satellite interpretations were provided by IOCC.
- Delayed Emergency Declarations: Crew delayed “Minimum Fuel” and “Mayday” calls beyond recommended thresholds.
- Jeopardized Diversions: Crew considered Kanpur and Prayagraj without onboard charts or FMS data for either location.
Contributing Factors
- Pressure to reduce fuel uplift likely influenced planning behavior.
- Confusing SOPs created mental fixation on a specific diversion plan.
- Heavy rain, low visibility, and communication delays worsened the situation.
DGCA and AAIB Findings
- The aircraft operated below fuel minima, in violation of CAR rules.
- Flight dispatch support was inadequate during a critical fuel event.
- The “Suitable vs Acceptable” alternate distinction introduced unnecessary risk.
- A forced landing or accident was narrowly avoided due to last-minute weather improvement at Lucknow.
Safety Recommendations
- Enforce dual-alternate policy during adverse weather.
- Clarify alternate definitions across all airline documentation.
- Require IOCCs to provide proactive, real-time satellite and radar updates.
- Mandate tracking of “Fuel Below Minima” incidents as a national safety indicator.
Conclusion
Vistara Flight 944’s July 2019 near-disaster offers critical lessons for airlines, flight dispatch teams, and regulators. Poor planning, weather misjudgments, and ambiguous policies created a situation where 162 lives were placed at risk.
The safe landing with just 348 kg of fuel was not just a feat of flying skill—it was a narrow escape made possible by a lucky window in the weather. India’s aviation industry must ensure that such close calls are not repeated.
Decoded from AAIB Full Report
