Crash of PIA Flight PK-8303 Brings Back Bitter Memories of Air India Express IX-812

What happened?

Pakistan International Airlines flight PK-8303 from Lahore to Karachi, an Airbus A320 (Registration AP-BLD) crashed near Karachi airport at about 1439 hours on May 22, 2020. As per reports, 89 passengers and 8 crew members perished in the crash. There were a total of 99 souls onboard (91 pax+8 crew). Two passengers survived miraculously.

PK 8303 crashed on its second approach after “going around” from a failed first attempt to land. The first approach was an an Instrument Landing System (ILS)-based approach for runway ’25 Left’ (ILS ‘Z’ 25L). The flight was flown under Intrument Flight Rules (IFR) that requires the aircraft to fly standard Air Traffic Service (ATS) route under ATC control, terminating in an instrument approach for the runway at destination, flying a specified profile (ILS Z, Rwy 25L for Karachi, in this case).

Instument approaches follow a published procedure after arriving via a Standard Arrival Route (STAR) or as guided by radar through ‘Radar vectors’. When flown correctly as per procedure, the instrument approach profile ensures terrain and obstacle clearance. Procedures internal to the cockpit are subject to guidelines from the aircraft manufacturer and company operations manual. Such procedures are designed to ensure crew coordination and aircraft configured for safe landing, flying down the published glide slope (3º GS for Karachi).

Karachi ILS 25L Approach Chart

The Jeppesen approach chart (also known as let-down chart) for runway 25L at Jinnah International Airport (OPKC), Karachi is shown below:

ILS Z Rwy 25L for OPKC Karachi Jinnah International Airport (Picture for representation only. Kindly use current authenticated chart for flying)

Approach plates such as the one above are designed to guide aircraft from initial approach to final approach, down to the runway. Such an approach may terminate in a landing or “go around” depending on internal / external situation. As such, the specified combination of heights and distances depicted on the chart are sacrosanct, with only very minor deviations allowed.

Energy management during approach

Since the published procedure has to cater for wide variety of aircraft, energy management (exchange of potential and kinetic energies in a safe and efficient manner during the approach) is left to the operator. There are strict guidelines laid down by each operator (based on type/make/model of airplane) that mandate a “go around” if breached. Instrument approaches involve intercepting the ILS Localiser first, then following LOC and intercepting the glideslope (GS), usually from below. Aircraft like B737 and A320 are flown using full automation, with a Pilot Flying (PF) and Pilot Monitoring (PM) concept, using standard callout and checklists, including mandatory “go around” criteria. This ensures optimum energy management (FSF ALAR Briefing Note 4.2), maximum safety and crew resource management.

Poor energy management on approach can lead to aircraft arriving at the desired landing point with too much or little energy. The former can lead to a long ‘float’, runway overrun, hard landing, or tail strike, while the latter can result in ‘undershoot’ or premature touchdown. Both can produce potentially disastrous outcomes, as proven by a high percentage of Approach and Landing Accidents (ALA).


Pakistan 8303 and Air India Express 812 Compared

PK 8303’s flight path on the first attempt to land brings back memories of the last major commercial airliner crash in India – Air India Express flight IX-812 (Regn VT-AXV, Mangalore-Dubai-Mangalore).

Both flights (IX-812 & PK-8303) resulted in tragedy that traces back to delayed descent, highly unstabilised approach, fixation on converting a bad approach into landing, and dogged reluctance to initiate “go around” in time.

While detailed accident report on IX-812 is available in open media, investigation into PK-8303 is underway. Based on information available at this time (May 27, 2020), rough parallels can be drawn between these two major accidents.

Type of aircraft

IX-812 was a Boeing 737-800 while PK-8303 was an Airbus A320-214. Both aircraft had CFM-56 engines (different variants though). A320 is a ‘fly-by-wire’ aircraft that employs ‘normal’, ‘alternate’ and ‘direct’ flight control laws with a descending order of flight envelope protection.

Type of approach

Both flights were cleared for an ILS approach. Air India Express IX-812 was cleared for ILS Rwy 24 at Mangalore via DME arc, whereas Pakistan International Airlines PK-8303 was cleared for ILS via localiser (LOC) for Rwy 25L at Karachi.

Minimum Sector Altitude (MSA)

Minimum Sector Altitude (MSA) is the lowest altitude which will provide a minimum clearance of 300 metres (1000 feet) above all objects located in the area contained within a sector of a circle of 46 km (25 Nm) radius centred on a radio aid to navigation or the Airfield Reference Point (ARP). This ensures terrain and obstacle clearance for IFR flights while crew manage their descent from cruising flight levels to initial approach altitude (IAA). The MSA may be different for different sectors depending on topography around the airfiled.

For IX-812 approaching Mangalore from northwest, it was 2000 feet while for PK-8303 approaching Karachi from Lahore, it was 2600 feet (hence the aircraft was cleared to descent to 3000 feet). The aircraft can be higher than MSA within 25 Nm (& often will be), but not lower. That would be unsafe and non-conformal to Standard Arrival Route (STAR) for IFR.

Final Approach Fix (FAF)

The aircraft may approach the destination from any direction, but finally passes through a point in space where it is aligned on the final approach course for the landing runway at the prescribed altitude in landing configuration. This point is known as Final Approach Fix (FAF). For IX-812, this was 5.8 Nm from the Mangalore VOR at 2200 feet, while for PK-8303 it was 6.1 Nm from LOC at altitude 2000 feet. Both IX-812 and PK-8303 passed well above the FAF during their approach.

Initial descent from cruise altitude

For modern aircraft with Flight Management System (FMS), the top of descent (ToD, where descent from cruise altitude is commenced) is easily available through the FMS. IFR approach checks include programming the FMS, selecting the runway, type of approach, STAR, specified reporting points/altitudes, etc.

Crew then obtain descent clearance from approach control or radar so that descent can be achieved as per SOP / ATC instructions. If for any reason, the intial descent is delayed, subsequent descent will invariably involve steeper descent angle and therefore higher ROD.

IX-812 descent was delayed by ATC as Mangalore Area Radar (MSSR) was unserviceable. They requested descent clearance at 130 miles from Mangalore but clearance was granted by ATC only at 77 Nm, almost at half the distance from intial request. This set the stage for a series of mistakes in a cockpit where “there was ‘no conversation’ between the two Pilots for the first 1 hour and 40 minutes of recording and the Captain was asleep with intermittent sounds of snoring”. (source: IX-812 final report)

PK-8303‘s flight took place after an unprecedented lockdown enforced by the CoVid-19 pandemic. All systems (crew, aircraft, ATC, maintenance, etc) were coming out of an extended period of grounding or ‘ deep slumber’, in a manner of speaking. Reported weather was fine and radar was ticking.

Plan view of IX-812 flight path versus approach plate of Mangalore ILS approach for Rwy 24 via DME arc (Pic from IX-812 accident report)

Arrival at key reporting points

For both IX-812 and PK-8303, trouble seems to have started when the aircraft failed to arrive at key points on the standard arrival pattern at specified altitude. As per available indications, both aircraft were consistently higher, sometimes twice the published altitude at places. This set up preconditions for an “unstabilised approach”.

Reasons why PK-8303 delayed their initial descent and ended up high in terminal stages of their flight is unknown. Perhaps, it was distraction caused due to a minor failure or some other event. With hardly any traffic at that time, arriving ‘high’ would likely attract both crew and ATC attention. It is quite likely that ATC would have cautioned PK-8303 crew of their unusually high altitude before they intercepted the localiser since it was a direct ILS approach. There is some evidence they did.

IX-812 was following a DME arc where they could continue their descent while on the arc without closing-in on the runway. But the accident report notes that “through out the descent profile and DME Arc Approach for ILS 24, the aircraft was much higher than normally expected altitudes.”

Unstabilised approach is leading cause of approach & landing accidents

IX-812:  Delayed descent exacerbated the situation for IX-812 on final approach. As per IX-812 accident report: “during approach, the CVR indicated that the Captain had selected Flaps 40° and completed the Landing Check List. At 06:03:35 hours IST at about 2.5 DME, the Radio Altimeter had alerted an altitude of 2500 ft. This was immediately followed by, the First Officer giving a call of “IT IS TOO HIGH” and “RUNWAY STRAIGHT DOWN”. In reply, the Captain had exclaimed “OH MY GOD”. At this moment, the Captain had disconnected the Auto Pilot and simultaneously increased the rate of descent considerably to establish on the desired approach path. At this stage, the First Officer had queried “GO AROUND?”

Despite three calls by the First Officer, IX-812 Captain persisted with the diving approach, reaching almost 4000 fpm descent rate and triggering numerous “SINK RATE” and “PULL UP” warnings from the EGPWS.

PK-8303:  The CVR and FDR of PK-8303 is yet to be decoded and will most likely contain the missing pieces. For reasons unknown at this point, PK-8303 persisted with the same fatal mistake as IX-812 of ‘diving’ to intercept the ILS glideslope from above. Were they facing some other abnormal situation that delayed their descent and distracted them from focusing on the approach? There was no radio call to this effect; but the call “we are comfortable, we can make it” perhaps indicates a request for landing clearance despite some event causing an unusually high arrival.

Altitude flight profile of PK-8303 (Copyright Aviation Safety Network)

ATC reacts affirmatively, but pilots manage to have their way

The Karachi controller was surely not happy or silent in complicity (unlike the controller at Mangalore for IX-812). At about 6 miles from touchdown, Karachi ATC instructed PK-8303 to “turn left heading 180”. ATC recording and flightradar24 data indicates that at 5Nm from touchdown, the aircraft was descending through 3500 feet instead of around 1700 feet (i.e, the aircraft was almost twice as high). It is inconceivable why the pilot should respond to ATC’s call at this point with “Sir, we are comfortable now, we are out of 3500 for 3000, established ILS 25 left”.

(The call “established ILS” means both localiser and glide slope have been captured. Ideally, at this distance and height, speed and descent rates should also be within required tolerances, with the aircraft correctly configured for landing – unlikely when the aircraft is diving at such high descent rate unless the pilots are hand-flying the aircraft or the system has captured a false glideslope.)

ATC call “Negative, turn left heading 180” indicates a second attempt by ATC to call off the approach. Controllers long enough in the game have several means to catch pilots’ bluff. Pilot continued to persist with “Sir, we ARE established on ILS 25 left”. This prompted the third and most damning query from ATC: “Sir, you are 5 miles from touchdown and still passing 3500”. A feeble “roger” response follows. At about 4Nm, aircraft altitude reduced to 1500 feet. This translates to an estimated descent rate between 4-6000 fpm depending on speed.

PK-8303 may have been plunging towards the runway at over 6 to 8 times the nominal ROD of 6-700fpm for a 3º ILS glideslope.

After a brief silence evoking no apparent reply from the crew, ATC played along with the bizarre sequence of events by the call “PK8303, cleared to land runway 25 left”. The pilots managed to have their way!

As opposed to the alacrity shown by Karachi ATC in the case of PK-8303, the ATC controller at Mangalore had radioed IX-812 to backtrack as per standard practice, unaware that the aircraft had overshot the runway and crashed into a gorge.

Doomed “Go Around” in both cases

There is no indication yet if PK-8303’s landing gear was down or up. Speed brakes and early deployment of landing gear can be used to increase the descent angle when required. But in a diving situation, even this may not be possible without exceeding the airspeed limits with gear extended. No caution about landing gear from an otherwise alert Karachi ATC is heard through this phase.

“Roger, Pakistan 8303”, responded the pilot to ATC’s landing clearance with a ‘Continuous Repetitive Chime’ (CRC) sounding in the cockpit. The CRC could indicate that the aircraft was not configured for landing or some other exceedance (gear malfunction or speed with gear, flaps exceeded?). It is also likely that such a precipitate dive would set off EGPWS warnings many times during the approach.

Every event in PK-8303’s approach, right from the time the aircraft first reported on ILS, appears to make an extremely strong case for applying TOGA power and going around.

Yet, for some inexplicable reason, they did not. A high-speed diving approach would invariably see the plane arriving over the runway too fast at high rate of descent. IX-812 accident bears this out, as would numerous ALA accidents. It is high school physics. Sample this snapshot from IX-812’s report that shows the profile and salient radio calls during their last moments:

Approach profile and salient CVR recordings of IX-812 (snapshot from IX-812 accident report)

Despite three distinct “go around” alerts from First Officer HS Ahluwalia, Captain Z Glusica of IX-812 decided to go around only after touching down more than halfway down the Mangalore runway and deploying thrust reversers (a prohibited manoeuvre). Pilot flying PK-8303 took the “8303 going around” decision after floating down the better part of the longer, 12000-feet Karachi runway. Somewhere during this aborted landing, PK-8303’s engines seems to have scraped the runway and sustained damage, as revealed by preliminary news reports citing CAA Pakistan. (Also view a comprehensive analysis here on Blancolirio channel.)

Runway Elevation & length

Elevation of both Mangalore and Karachi airports are comparable: 320 feet and 100 feet respectively. However, a key difference is that Mangalore has a “table-top” runway with hills nearby, whereas Karachi airport is in the plains. Both airports are close to the sea. Mangalore airport required special clearance and Captain’s landing. Karachi is also significantly longer (12000 feet) as compared to Mangalore (8000 feet), denoting little more leeway to the pilot in deciding land/go around.

Final Moments

The end came quickly thereafter for IX-812. The aircraft overshot runway, right wing impacted the localiser antenna, aircraft tore through the boundary fence and fell into a gorge, leading to 158 deaths. IX-812 report noted that “during the entire period of CVR and ATC Tape recording, there was no emergency call from the aircraft indicating any type of failure.”

As compared to this, PK-8303 managed to lift off Rwy 25, struggled to reach about 2000 feet and sought another ILS approach. During this phase, their troubles seem to have rapidly compounded, possibly due to engine damage sustained during ground contact. The flight path also raised ATC’s attention with couple of cautions for altitude, clearing a lower altitude (2000 feet), followed by a query “ehh…appears to be turning left?” To this, the pilot replied “Affirm…we’ll (be) proceeding direct, sir; we have lost the engine(s)”, declaring for the first time that something was seriously amiss.

ATC answered with the query “confirm you are carrying out belly landing?”, indicating that gear was up at that time (or earlier). During a power-off glide, banking or degrading the lift-to-drag ratio only increases descent rate. PK-8303 was probably doomed by then with no ‘Miracle on the Hudson‘ in sight.

Between 3-4 minutes after going around, PK-8303 declared “Mayday mayday mayday Pakistan 8303”, crashing soon after into a crowded residential colony “just before the runway”. CCTV footage of moments before ground impact shows aircraft descending sharply with high nose-up attitude, indicating a failed effort to extend the glide after losing engine thrust. Some shutterbugs captured the aircraft with its Ram Air Turbine (RAT) deployed, further corroborating the engine failure hypothesis.

Too early to conclude, but unstabilised approach sure to figure in this ALA

Approach and landing is a high-risk phase of flight, accounting for over 50 percent of all accidents. Investigation into PK-8303 crash will add another data point to this statistic. In 1988, the Flight Safety Foundation (FSF) published an Approach and Landing Accident Reduction (ALAR) tool kit after comprehensive study by an international task force. Interested readers can access many valuable resources connected with this study through this link here. Meanwhile, PK-8303’s FDR has been recovered and an investigation is underway, as per reports.

As aviation worldwide dusts itself out of an unprecedented lockdown, it is worthwhile revisiting key lessons from the past.

It is ironic that Pakistan PK-8303 crashed at Karachi exactly ten years after Air India IX-812 met a fiery end at Mangalore in the wee hours of May 22, 2010.

Investigations must delve deep into the details, including human factors and failures at every level, that led to this infinitely sad but wholly avoidable crash just a day before the the holy month of Ramadan ended for believers.

Blue skies. Khuda Hafiz.

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©KP Sanjeev Kumar, 2020. All rights reserved. I can be reached at kipsake1@gmail.com. Views expressed in this article are personal, except where quoted from sources. Feedback is welcome. Kindly keep the comments clean and respectful of victims and their families.

Cover image of PIA AP-BLD is a representational photo from 2016 (Pic courtesy Shadman Samee from Dhaka, Bangladesh via Wikipedia CC BY-SA 2.0)

 

4 thoughts on “Crash of PIA Flight PK-8303 Brings Back Bitter Memories of Air India Express IX-812

  1. Looks more likely catching false glide slope and not cross checking GS heights
    Finally realized on ATC call there after tried to manually hack it but couldn’t manage and leading to engine scrape and subsequent fail

    1. There was something on youtube about PIA having issued a circular banning the use of TOGA by its pilots.

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