Tomark Viper Sd-4 (SD4)
i
ICAO SD4 Small

Tomark Viper Sd-4

Single Piston

The Shorts 360 is a boxy, high-wing regional turboprop that became a workhorse of short-haul commuter aviation in the 1980s and early 1990s. Built by Shorts Brothers in Belfast, Northern Ireland, the SD3-60 variant seated up to 36 passengers and was powered by twin Pratt & Whitney Canada PT6A-65R turboprops. Its distinctive squared-off fuselage (earning it the nickname "flying shoebox") was optimized for cargo volume and ease of loading, making it equally popular with freight operators and passenger carriers serving thin routes. The type entered service in 1982 as an enlarged successor to the Shorts 330, offering better performance and cabin comfort while retaining the rugged simplicity that made Shorts aircraft favorites for rough-field operations. The 360's design prioritized utility over speed. With a maximum cruise of around 210 knots and a range of roughly 450 nautical miles at full payload, it was never meant to compete with sleeker turboprops like the Saab 340 or ATR 42. Instead, it excelled at short hops between regional airports, often operating from unpaved or minimally equipped strips where its high wing and sturdy landing gear were assets. The cockpit featured straightforward analog instrumentation and required a two-pilot crew, though the aircraft's handling characteristics were forgiving and well-suited to less experienced first officers building turboprop time. Production ended in 1991 after 165 aircraft were built, but the type soldiered on in cargo and charter roles well into the 2000s. Many were converted to freighters, where the capacious cabin and rear cargo door proved ideal for express parcels and overnight mail. By the 2010s, most passenger examples had been retired from scheduled service, replaced by more fuel-efficient regional jets and modern turboprops, though a handful remain active in niche markets. The 360 never achieved the commercial success of its competitors, but it carved out a loyal following among operators who valued its load-carrying ability and no-nonsense engineering. SkyMeter has tracked 286 flights across 42 airframes and 7 operators, with PISTON AVIATION LLC the largest observed operator.

✈
ACTIVE AIRFRAMES
42
last 7 days
🏢
OPERATORS
7
unique airlines
📊
FLIGHTS
286
tracked
⏱
AVG DURATION
32m
per flight
⚠
INCIDENT RATE
2.1%
6 flagged
ⓘ

Safety in context

The incident rate counts flights with ANY safety event detected by SkyMeter: go-arounds (a routine response, not a failure), unstable-approach gate flags (advisory thresholds), rejected takeoffs (the system working as designed), and runway events. It is NOT an accident rate or fatality rate. For accident statistics, refer to the NTSB Aviation Accident Database (USA) or the Aviation Safety Network. See methodology for what each event type measures.

Performance

Speed envelope & approach

Vref
50 kt
Vref range
—
Vmo
230 kt
Mmo
—
Vs1 (clean)
78 kt
Vs0 (landing)
68 kt
Vfe
140 kt
Approach category
A

Dimensions

Airframe geometry

Wingspan
—
Length
—
Tail height
—
Wheelbase
—
Gear width
—
Wake category
Light

Weight & identification

Operating limits

MTOW
1,212 lb
MALW
—
Manufacturer model
Tomark Viper SD-4
FAA designator
SD4
Registered
—

Recent incidents

Flagged flights of SD4

20
10/18/2026
36m
△ Low approach-stability score
10/15/2026
3h 38m
! Stall
10/12/2026
36m
△ Low approach-stability score
10/11/2026
37m
! Stall△ Low approach-stability score
10/11/2026
46m
△ Low approach-stability score
10/10/2026
52m
△ Low approach-stability score
10/10/2026
26m
! Stall

Recent flights

Real flights of SD4 · airborne ≥ 20 min

30
10/19/2026
52m
No alerts
10/19/2026
22m
No alerts
10/19/2026
28m
No alerts
10/19/2026
28m
No alerts
10/19/2026
25m
No alerts
10/19/2026
28m
No alerts
10/19/2026
58m
No alerts
10/19/2026
1h 4m
No alerts
10/19/2026
1h 5m
No alerts
10/19/2026
19m
No alerts
10/19/2026
57m
No alerts
10/19/2026
1h 1m
No alerts
10/18/2026
42m
No alerts
10/18/2026
22m
No alerts
10/18/2026
30m
No alerts
10/18/2026
1h 42m
No alerts
10/18/2026
57m
No alerts
10/18/2026
36m
△ Low approach-stability score
10/18/2026
1h 3m
No alerts
10/18/2026
39m
No alerts
10/18/2026
1h 22m
No alerts
10/18/2026
20m
No alerts
10/18/2026
1h 16m
No alerts
10/18/2026
1h 53m
No alerts
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© SkyMeter · All flight data subject to ODbL attribution · Tracking window: 7 days (free tier)