Investigators have determined that the complex failure of a Pakistan International Airlines ATR 42-500’s left-hand engine preceded a loss of control which developed into a stall, loss of altitude, and eventual fatal collision with terrain. At one point in the accident sequence the aircraft inverted as it underwent a full 360° roll to the right, continuing to roll another 90° before banking left until it was wings-level – losing some 5,100ft in height overall. The ATR (AP-BHO) had been operating from Chitral to Islamabad on 7 December 2016, its sixth flight of the day, with 42 passengers and a crew of five. Pakistan’s aircraft accident investigation board says the aircraft probably took off with a fractured stage-one power turbine blade in its left-hand Pratt & Whitney Canada PW127E powerplant. It believes the blade “probably” fractured or dislodged during the previous flight, from Peshawar to Chitral. The engine had been installed three weeks earlier, having been taken from another of PIA’s ATRs (AP-BHP) during unscheduled maintenance. During this work the power turbine assembly was removed. But while the turbine blades had passed the 10,000h criteria for replacement, the inquiry says they “were not replaced”. The engine operated for a further 93h before the onset of the emergency. Over the initial 26min of the flight to Islamabad – with the ATR cruising at 13,500ft – there was evidence that the left-hand propeller’s speed governing accuracy had degraded, but this was not noticed by the crew. The aircraft was cruising at 186kt instead of the expected 230kt. The inquiry says a series of technical malfunctions then occurred to the engine and its propeller control system. Fracture of the turbine blade unbalanced the power turbine, and the situation was further complicated by another latent problem, a broken pin in the engine’s overspeed governor, as well as oil contamination. The resulting technical malfunction generated an increase in propeller pitch and an unusual decline in propeller speed – from the cruise level of 82% it fell to 62%. “Due to this combined technical anomaly, during following parts of the flight, the conditions were exceptionally difficult,” says the inquiry, pointing out that the aircraft suffered “uncontrolled variation” in its propeller speed and blade pitch. Propeller speed increased to 102%, before falling, while the blade pitch reached a point possibly close to the feather position. The propeller speed unexpectedly increased again, corresponding to an unfeathering, reaching 120-125%. The left side of the aircraft produced “high drag values”, says the inquiry, while the crew had not responded with sufficient power, resulting in falling airspeed and the aircraft flying on the verge of stalling, at around 120kt, its stick-shaker activating. Advancement of power on the right-hand engine, it says, coupled with “excessive” right rudder to counter the asymmetric condition, coincided with an “abrupt” fall in the left-hand propeller speed. “A considerable amount of drag was eliminated from the left side of the aircraft,” says the inquiry, and the crew’s efforts to maintain directional control suddenly became “surplus to the requirement” – resulting in a sharp yaw to the right, the inverting roll and rapid descent, the aircraft losing 5,100ft before recovering at 8,350ft. “This had immense psychological impact on the cockpit crew, and it impaired their capacity to perform normally,” says the inquiry. After the recovery, complex simulations indicate the aircraft’s propeller blades might have settled at a low pitch while rotating at about 5%, generating stable drag forces on the left side. But the aircraft’s behaviour was different to that which would have been expected during a standard in-flight shutdown and single-engined operation, with propeller drag some seven times more than it would normally produce once feathered. “In this degraded condition it was not possible for the aircraft to maintain a level flight,” says the inquiry. It could only fly in a gradual descent of 800-1,000ft/min at around 150-160kt. Directional control was possible with “substantial” right rudder and right aileron inputs, it adds, but the pilots were “unable to judge” the nature and extent of degradation in the aircraft’s aerodynamic performance. When the crew attempted to reduce the rate of descent, the airspeed also began to fall. Despite progressively-increasing control inputs to the right, the aircraft entered a continuous left turn, approaching high terrain and triggering ground-proximity warnings. The airspeed declined and the aircraft stalled at 4,280ft – just 850ft above ground – rolling 90° to the left and pitching 23° nose-down before striking a mountain base 42min into its flight.
None of the occupants survived the impact, some 24nm north of Islamabad airport and 3.5nm south-south-east of Havelian.

Source: Cirium

The Covid-19 pandemic has certainly stricken the passenger airline industry. But the air cargo segment has been a rare beneficiary, with e-commerce sales and scarcity of widebody passenger jets driving up cargo yields and demand for cargo jets, according to Boeing’s 20-year cargo outlook. Boeing had already, in early October, released cargo-jet demand projections as part of a broader 20-year commercial aviation outlook. But Boeing’s just-released cargo-specific outlook provides more insight into factors driving demand, such as the pandemic. Overall, air cargo capacity is down 25% since January. But strong demand has pushed up cargo revenue 16%, with yields jumping 42%, Boeing says. During the next 20 years, the Chicago airframer anticipates airlines will need 2,430 additional cargo aircraft, among them 930 new widebodies and some 1,500 jets converted from passenger to cargo aircraft. Boeing anticipates strong demand in the coming years for 777Fs and 767Fs. And though the 767F is an ageing design – Boeing delivered the first of the type in 1982 – it could remain in production for the foreseeable future, says Boeing vice-president of commercial marketing Darren Hulst. “I think that continues through this decade,” he says of the 767. Boeing holds outstanding orders for 80 767s, including 49 cargo variants, most for UPS and FedEx. The remainder are military variants, according to Boeing’s website. Boeing also produces 747-8Fs (but expects to stop manufacturing that jet in 2022), and speculation abounds about whether Boeing will develop a freighter variant of its 777X. The forecasted 2,430 new and converted freighters would bring the global air freighter to 3,260 aircraft by 2039, up from 2,010 today, Boeing predicts. The Covid-19 pandemic has been a primary short-term driver of freighter demand, as has e-commerce, says Hulst. “We’ve seen a growth in the number of aircraft operated as freighters. Aircraft have been taken out of storage, reactivated to fly because of demand for air cargo,” he says. “Airlines, freighter operators [and] wet-lease operators have been using their fleets about 20% more than normal.” The need for more freighters stems from the sharp decline in the number of widebody passenger aircraft plying the globe’s skies. Carriers took many widebody jets out of service amid the pandemic, resulting in a roughly 60% year-on-year decline in available cargo space in the bellies of those jets. All-cargo jets have picked up some of the slack; capacity in those aircraft is up 13% year-on-year, Boeing says.

Source: Cirium

Asiana Airlines — most recently the subject of an acquisition by rival Korean Air — swung back into the black in its third-quarter earnings, helped by an uptick in cargo revenue and a steep reduction in costs. For the quarter ended 30 September, the carrier eked out an operating profit of W5.8 billion ($5.2 million), reversing the W45.1 billion loss it made during the same period last year. Revenue fell 53% year-on-year to W731 billion, led mainly by a collapse in passenger travel demand, which plummeted 83% year-on-year. Broken down by network, international passenger revenue saw a sharp 87% plunge year-on-year to W122 billion, while domestic passenger revenue fell 42% to W50.3 billion. However, any further decline was offset by a 54% increase in cargo revenue to W485 billion for the quarter. Expenses declined 55% year-on-year to W725 billion, which Asiana notes stemmed from reduced flying activity. The Star Alliance carrier also swung back to a net profit of W2.3 billion for the quarter, reversing last year’s net loss of W170 billion. Domestic RPKs for the period slipped 27% year-on-year, while ASKs fell 14%. The carrier reported a domestic passenger load factor of 74%, about 13 percentage points lower compared to the same quarter last year. International RPKs, meanwhile, plunged 93% year-on-year, with ASKs declining 79%. Load factor for the quarter stood at just 27%, 56 percentage points lower year-on-year. Asiana’s third-quarter earnings come days after rival Korean Air announced it would be acquiring the troubled carrier. The deal, worth some W1.8 trillion, ends months of speculation about who would be Asiana’s new owners, after failed attempts by parent company Kumho Industrial to sell its controlling stake.

Source: Cirium