Resulting Safety Initiatives

Since the Indian Airlines Flight 605 accident, highly integrated airplanes like the A320 have become more prevalent in the world fleet. A number of gaps in the areas of crew interfaces in highly automated airplanes have become apparent. The industry at large has taken steps to address these issues. New regulatory material has been developed with the intent to minimize crew error when using installed equipment, and advisory material has been widely distributed by a number or entities and organizations to close those perceived gaps.

Flight Manual Changes

Following the accident, Airbus issued a new flight manual limitation that restricted the use of autopilot or flight directors in DES or OPEN DES mode below 500 feet above the ground, or the minimum descent altitude (MDA) on an approach, whichever is higher.  Though this limitation was not made mandatory by airworthiness authorities, it has been distributed to all A320 operators.

Regulations

14 CFR 25.1302 Installed Systems and Equipment for Use by the Flightcrew

Advisory Circulars

AC 25-11A Electronic Flight Deck Displays
AC 25.1302-1 Installed Systems and Equipment for Use by the Flightcrew
AC 25.1329-1B Approval of Flight Guidance Systems
AC 120-71A Standard Operating Procedures for Flight Deck Crewmembers
AC 120-51E Crew Resource Management Training

Safety Initiatives

Design Changes

Photo of airspeed tape showing extended speed reference line
Photo of airspeed tape showing extended speed reference line

Subsequent A320 system enhancements made in regards to the A320 Airspeed Display and Low Airspeed Awareness include the following;

  • The readability of the actual airspeed was enhanced by extending the airspeed reference line across the entire width of the airspeed tape. The airspeed display on the left is how the airspeed reference line was displayed during the Indian Airlines Flight 605 accident.
  • "Low energy awareness" is enhanced with an automatic aural warning of "Speed, Speed, Speed" when airspeed decreases below the Low Energy Warning Threshold. Unlike Alpha Floor, the low energy warning is available in degraded flight control law configurations. The low energy warning detection is active when the aircraft is below 2000' and above 100' AGL, flaps are in Config 2 or greater, and Alpha Floor is not engaged. This "SPEED" warning is designed to alert the flight crew so they can preemptively act to avoid triggering Alpha Floor.

Subsequent A320 system enhancements made in regards to the autothrust system include the following;

  • Autoflight thrust/vertical modes will change from "Idle - Open Descent" to "Speed - Vertical Speed" if the Speed decreases to VLS. The Autothrust System will then maintain the selected speed and the Flight Director will provide commands to maintain the actual vertical speed at the time of the reversion.
  • When the FCU selected altitude is changed while in ALT*, the autoflight system will revert to Speed-V/S instead of reverting to Idle - Open Descent.
  • An "IDLE" Indication is displayed on the E/WD engine instrument displays when engine thrust is idle.
  • Engine thrust Approach Idle settings for the V2500 engines was increased by 2.5%. This modification was associated with CAT III certification and was not specifically related to the Bangalore event.

If the Indian Airlines accident scenario (with IDLE / OPEN DESCENT; left Flight Director OFF and right Flight Director ON) were to occur in an A320 with the most current Auto-Flight System software, the following would now occur;

  • If the FCU selected altitude is changed while in ALT*, the autoflight system will revert to Speed-V/S instead of reverting to Idle - Open Descent.
  • If still in IDLE / OPEN DESCENT and speed decreasing, Autoflight thrust/vertical modes will change from "Idle - Open Descent" to "Speed - Vertical Speed" when the Speed decreases to VLS. Also, both flight directors will be removed from display (disabled) and both PDF FMA columns 2 (vertical guidance) and 3 (lateral guidance) will be blank. Thrust will come up to control to the target speed (Vapp).

Low Speed Awareness

Flight Deck Automation / Flight Deck Design / Systems-Avionics Confusion

ICAO CIRCULAR 234-AN/142 - HUMAN FACTORS DIGEST No. 5  -  OPERATIONAL IMPLICATIONS OF AUTOMATION IN ADVANCED TECHNOLOGY FLIGHT DECKS  -  1992  -  Discusses Human Factors implications of automation and advanced technology flight decks.

FAA Human Factors Team Report on The Interfaces Between Flight Crews and Modern Flight Deck Systems - June 18, 1996  - Study evaluating the flightcrew/flight deck automation interfaces of current generation transport category airplanes.  (Indian Airlines Flight 605 is referenced in the report.)

Airbus Safety Library Publications:

Operations Golden Rules - Discusses proper use of automation and flight guidance
Optimum Use of Automation 
Human Factors Aspects in Incidents/Accidents 

Flight Safety Foundation Publications:

Flight Safety Foundation (FSF) Approach and Landing Accident Reduction (ALAR) Briefing Note 2.1 – Human Factors – Flight Safety Digest, August – November 2000. - Human Factors involvement in aviation accidents. 

Flight Safety Foundation (FSF) Approach and Landing Accident Reduction (ALAR) Briefing Note 1.2 – Automation – Flight Safety Digest, August – November 2000.  - Involvment of automation in approach and landing accidents

Crew Resource Management / Incorrect Pilot Technique Accidents

Airbus Safety Library Publications:

CRM Aspects in Incidents/Accidents 

Flight Safety Foundation Publications:

Flight Safety Foundation (FSF) Approach and Landing Accident Reduction (ALAR) Briefing Note 2.2 – Crew Resource Management – Flight Safety Digest, August – November 2000. 

Flight Safety Foundation (FSF) Approach and Landing Accident Reduction (ALAR) Briefing Note 1.3 – Golden Rules – CRM and Automation – Flight Safety Digest, August – November 2000. 

Flight Safety Foundation (FSF) Accident Prevention, Vol 51, No 1, Jan 1994 – Cockpit Coordination, Training Issues Pivotal in Fatal Approach-to-Landing Accident - Detailed discussion of the Indian Airlines Flight 605 accident.

Unstabilized Final Approach

Airbus Safety Library Publications:

Flying Stabilized Approaches

Aircraft Energy management during Approach

Flight Safety Foundation Publications:

Flight Safety Foundation (FSF) Approach and Landing Accident Reduction (ALAR) Briefing Note 7.1 – Stabilized Approach – Flight Safety Digest, August – November 2000. 

Back to top