ALTIMETERY

ALTIMETERY. PRESENTED BY GUIDED BY SHRIKANT VADNAL, SM , HAL WG CDR AJAY NAUTIYAL PRANJALI PATHAK, AAO, HAL DS,ATCOTE.

[Audio] ALTIMETER IS A DEVICE WHICH MEASURES PRESSURE AND DISPLAYS THE CORRESPONDING PRESSURE ALTITUDE.

TYPES OF ALTITUDES. True Altitude - Altitude above the MSL Absolute Altitude – Altitude above the ground level Indicated Altitude - Displayed on the altimeter Pressure Altitude -The height above a standard datum plane which is a theoretical level where weight of the atmosphere is 29.92 mm of Hg (1013.2 mB ) as measured by a Barometer. Density Altitude – The air density given as a height above MSL.

TYPES OF ALTITUDES. A picture containing timeline Description automatically generated.

TYPES OF ALTIMETERS. RADIO ALTIMETER It is an airborne electronic device capable of measuring the height of the aircraft above the terrain immediately below the aircraft..

TYPES OF ALTIMETERS. BAROMETRIC ALTIMETER It consists of a barometric capsule linked to a pointer by a suitable mechanical or electronic system. The pointer moves across the dia in response to the changes in barometric pressure.The dial is caliberated in feet or in meters..

INDICATED ALTITUDE VARIATION. With Temperature. Diagram Description automatically generated.

INDICATED ALTITUDE VARIATION. With Pressure. A picture containing text, watch Description automatically generated.

SUBSCALE SETTING IN ALTIMETER. Aircraft pressure altimeters indicate the elevation of the aircraft above a defined datum. The datum selected depends on the barometric pressure set on the altimeter subscale. ICAO has designated some codes call the Q codes and they are defined in PANS-OPS Doc 8400. QNH – Altimeter subscale setting to obtain elevation when on ground. QNE – Altimeter Subscale setting to standard value 1013.2 mB QFE – Atmospheric pressure at aerodrome elevation (or the runway threshold) QDR – Magnetic Bearing QDM – Magnetic heading.

TRANSITION ALTITUDE AND TRANSITION LEVEL. Transition Altitude – The altitude at or below which the vertical position of an aircraft is controlled by reference to altitudes Transition Level – The lowest Flight level available above the transition altitude.

CAUSES OF ALTIMETER ERRORS. Aircraft altimeters are subject to the following errors and weather factors Instrument error Position error from aircraft static pressure systems Non-standard atmospheric Pressure Non-standard temperatures.

HOW COMMON ARE THE ALTIMETER ERRORS?. Some of the recent accidents or incidents including error in altimeter are - Etihad cargo flight low approach caused by incorrect altimeter setting, Abu Dhabi Airport, June 6 2020, 1001 UTC. Antonov 72 of Kazakhstan Border Guards, crashed 20 km from Shymkent Aiport, Kazakhstan on December 25,2012 Near Collision between inbound A318 at Bordeaux, France and a Pilatus PC-12 which was on a ferry to San Sebastian, Spain on June 02 2010 Turkish Airlines Flight 1951, Amsterdam Schiphol Airport, February 25 2009..

CASE STUDY – Turkish Airlines Flight 1951 Crash. Turkish Airlines Flight 1951 (also known as the Poldercrash or the Schiphol Polderbaan incident ) was a passenger flight that crashed during landing at Amsterdam Schiphol Airport, the Netherlands, on 25 February 2009, resulting in the deaths of nine passengers and crew, including all three pilots. The aircraft, a Turkish Airlines Boeing 737-800, crashed into a field about 1.5 km (0.9 mi) north of the Polderbaan runway(18R), having flown from Istanbul,Turkey. The aircraft broke into three pieces on impact. The wreckage did not catch fire..

CASE STUDY – Turkish Airlines Flight 1951 Crash. The crash was caused primarily by the aircraft's automated reaction, which was triggered by a faulty radio altimeter. This caused the auto throttle to decrease the engine power to idle during approach. The crew noticed this too late to take appropriate action to increase the thrust and recover the aircraft before it stalled and crashed. Boeing has since issued a bulletin to remind pilots of all 737 series of the importance of monitoring airspeed and altitude, advising against the use of autopilot or auto-throttle while landing in cases of radio altimeter discrepancies..

CASE STUDY – Turkish Airlines Flight 1951 Crash. Video.

CONCLUSION.