Accident Junkers Ju-52/3mg4e HB-HOT,

ASN Wikibase Occurrence # 319594

Date:	Saturday 4 August 2018
Time:	16:56
Type:	Junkers Ju-52/3mg4e
Owner/operator:	Ju-Air
Registration:	HB-HOT
MSN:	6595
Year of manufacture:	1939
Total airframe hrs:	10189 hours
Cycles:	8783 flights
Engine model:	BMW 132A3
Fatalities:	Fatalities: 20 / Occupants: 20
Aircraft damage:	Destroyed, written off
Category:	Accident
Location:	1,2 km SW of Piz Segnas - Switzerland
Phase:	En route
Nature:	Passenger - Non-Scheduled/charter/Air Taxi
Departure airport:	Locarno Air Base (LSMO)
Destination airport:	Dübendorf Air Base (LSMD)
Investigating agency:	STSB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
A Junkers Ju-52/3m aircraft, operated by Ju-Air, was destroyed in an accident in a mountainous area in Switzerland. The aircraft crashed into the western slope of Piz Segnas at an elevation of 2540 m. All 17 passengers and three crew members were killed.
The aircraft had departed Locarno, Switzerland, at 16:10 on a flight to its home base at Dübendorf.
The aircraft flew on a northeasterly course into the basin southwest of Piz Segnas. Towards the north end of the basin, it began a left turn, which developed into a descending spiral trajectory. A short time later, the aircraft collided with the ground almost vertically and at high speed.
Following the crash, all Swiss Junkers Ju-52 aircraft were grounded. Ju-Air was allowed to restart operations on August 17 with the two remaining aircraft of the same type. Since there were no indications of general technical defects at this time, the FOCA had approved the resumption of flight operations in compliance with precautionary measures.
On November 20, the Swiss TSB published an interim report. There was still no evidence that a serious technical problem led to the accident. The investigation of the wreck, however, revealed severe structural damage in the form of cracks and corrosion on the main spar, the supporting element of the aircraft wing, and other parts of the aircraft. This damage was hidden during normal inspections and maintenance and could only be determined from the debris.
Since the two Ju-52 HB-HOP and HB-HOS stationed in Dübendorf correspond in age as well as in hours of operation to the crashed aircraft, the Swiss authorities temporarily grounded both aircraft for inspections.

Direct cause:
The accident is attributable to the fact that after losing control of the aircraft there was insufficient space to regain control, thus the aircraft collided with the terrain.

The investigation identified the following direct causal factors of the accident:
- The flight crew piloted the aircraft in a very high-risk manner by navigating it into a narrow valley at low altitude and with no possibility of an alternative flight path.
- The flight crew chose a dangerously low airspeed as regard to the flight path.
Both factors meant that the turbulence which was to be expected in such circumstances was able to lead not only to a short-term stall with loss of control but also to an unrectifiable situation.

Directly contributory factors
The investigation identified the following factors as directly contributing to the accident:
- The flight crew was accustomed to not complying with recognised rules for safe flight operations and taking high risks.
- The aircraft involved in the accident was operated with a centre of gravity position that was beyond the rear limit. This situation facilitated the loss of control.

Systemic cause
The investigation identified the following systemic cause of the accident:
- The requirements for operating the aircraft in commercial air transport operations with regard to the legal basis applicable at the time of the accident were not met.

Systemically contributory factors
The investigation identified the following factors as systemically contributing to the accident:
- Due to the air operators inadequate working equipment, it was not possible to calculate the accurate mass and centre of gravity of its Ju 52 aircraft.
- In particular, the air operators flight crews who were trained as Air Force pilots seemed to be accustomed to systematically failing to comply with generally recognised aviation rules and to taking high risks when flying Ju 52 aircraft.
- The air operator failed to identify or prevent both the deficits and risks which occurred during operations and the frequent violation of rules by its flight crews.
- Numerous incidents, including several serious incidents, were not reported to the competent bodies and authorities. This meant that they were unable to take measures to improve safety
- The supervisory authority failed to some extent to identify the numerous operational shortcomings and risks or to take effective, corrective action.

Accident investigation: