Afgespeeld
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29 March 2015 A320 Toronto - Halifax Winter time, forecast in Halifax wind 15kts G25 with moderate drifting snow and a temp of -5 and vis 1/2sm (800m). In cruise, received METAR 1/4sm vis (400m) with heavy snow
NOTAMED that Glide path U/S so they set up for a LOC only. Calculated cold temp correction for FAF alt, MDA and GA alt. Calculated FAF to be 2200ft ASL (+200ft correction)
MDA they added 23ft for temp and 50ft for the company see FCTM - SI -010 (approach) Using their company qrh converter the adjusted the FPA from 3.1 to 3.5° In level flight before reaching the FAF they pulled FPA and selected 0
0.3nm before FAF they selected fpa -3.5 As the a/c descended it diverged from the desired profile due to wind variations. This divergences continued throughout the approach. A 400’ auto call out was made as they descended through MDA 1.2nm from threshold PM called “minimum, lights only” as per their SOP. The aircraft was 1nm from the threshold now. PF saw the approach lights and called landing At MDA the aircraft was 0.3nm further back than published At 0.7nm from threshold crew confirmed visual with the approach lights. The reports says they were over a lighted facility. AP was disconnected just above 100' RA At the 50ft auto callout the PM called "pull up" The aircraft struck and severed a power line that was perpendicular to the runway causing power outage to the terminal TOGA was selected about 1 second before ground impact and a full, pull up, demand was made on the side stick. The left landing gear struck an approach light about 860ft before the threshold. Then the main landing gear, aft fuselage and the left engine hit the snow covered ground, bounced, took out the LOC antenna, bouncing twice more before skidding along the runway, coming to rest about 1900ft after the threshold. Power to the aircraft was lost during the ground contacts leaving only the emergency lights on in the cabin. Pax were evacuated successfully with no deaths. 1 cabin crew member was seriously injured and the were 25 minor injuries. The flight crew were pretty experienced with the Captain having over 5700 hours and the FO 6300 hours on type. Errors/factors
The Auto pilot limitation on a NPA is AT MDA. AP was actually disconnected 23 seconds after passing MDA
Didn't monitor DIST/ALT table on chart. "At Air Canada, the use of dist/alt table on jepp charts as a monitoring tool is not cited during pilot training fro loc/npas
CT (canadian CAA/FAA) didnt raise this as an issue at any inspections.
This is critical because of the limitations of the FPA According to the report, Air Canada pilots didnt have access to the FCOM, only the company manuals.
FCOM doesnt offer any guidance on how to adjust the FPA e.g how much for how long. For your info, 0.1º change will affect the a/c path by 10ft over the next NM so for example if youre on a 3º glide and youre 30ft high at a height check, increasing the FPA to will get you back on profile in 1 NM. so 0.1º per 10ft. just remember to reset to 3º once its back on profile! Contrary to this, "air canada's practice was the, once the a/c was past the FAF, flight crews were not required to monitor the a/c's alt and dist from the threshold, nor make any adjustments to the FPA. Also, Airbus said at the time that before the FAF press TRK/FPA pb, select desired FPA on the FPA dial and then at 0.3 before the FAF - pull. Air canadas practice was to pull v/s/FPA selecting 0 and then wind it to desired angle at FPA -0.3 Unlike EASA and FAA, in canade the minimum vis for an approach isnt afected by the type of ALS installed. As a comparison, for the minima at halifax the FAA would require an additional 900m of approach lighting!!You can read the report yourself by clicking on this link:
http://www.bst-tsb.gc.ca/eng/rapports-reports/aviation/2015/a15h0002/a15h0002.asp
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This week Matt and Andy take a look at the Flight Augmentation Computers and their functions.
New Airbus manuals are now released and on their way to airlines around the world. Your airline should be updating them soon if they haven't already. There's an episode about this change TAP030 so have a listen to refresh your memory.
The A320 has two FACs (flight augmentation computers) and they have three main functions, - Yaw functions (your damping, rudder trim and rudder trim limiting)
- Flight envelope functions
- Windshear detection
The FACs govern the flight envelope, rudder position display and rudder trim indications regardless of what the flight crew does with the FAC pushbutton. It also controls the speed scale.
FAC Computes:
VSW
VLS
VFE & VFE NEXT
VLE
VMO/MMO
GREEN DOT
S SPEED
F SPEED
TREND ARROW
Alpha lock
This function inhibits slat retraction at high angles of attack and low speeds. When the flat leave is set to 0, the alpha/speed lock function activates and inhibits slat retraction if:
The angle of attack is greater than 8.5° or
The speed is less than 148 kts.
If the flap lever is already set to 0 (so the slats are moving or are already at 0) when the alpha lock conditions occur, inhibit will not activate therefore the stats will continue to retract or remain at zero.
Once the alpha/speed lock function is active, the slats will only retract when:
The angle of attack is less than 7.6° and,
This speed is above 154 kts
The function is not active on the ground when the speed is less than 60kts.
Links - www.planetalkinguk.com
Their mission statement says "To produce you, our loyal listener, a weekly rundown of the important aviation-related news stories that matter to us here in the UK."
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This week Matt discusses a windshield failure which also damaged the FCU causing the loss of autopilot!
http://avherald.com/h?article=4b890953&opt=0
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This week Matt and Andy discuss the windshear detection systems on the A320
