FIER WILLIAM J· ICAO24 a48166· last seen 1d ago

N39KW is a Van's Aircraft RV-4, a single-engine piston aircraft operated by FIER WILLIAM J. SkyMeter has tracked 102 flights totalling 38 hours of airtime via ADS-B. The most frequent segment is K84R to KHYI. Service window in our records spans 449 days. Of those flights, 20 (19.6%) carry at least one detected incident: a go-around, unstable approach, stall warning, or runway excursion. The Van's Aircraft RV-4 has a maximum takeoff weight of 1,500 lb, light wake category.

About the Van's Aircraft RV-4

The Van's RV-4 is a tandem two-seat homebuilt aircraft that established Van's Aircraft as the dominant force in kit aviation when it debuted in 1979. Designed by Richard VanGrunsven, the RV-4 was the first Van's model to achieve widespread success, combining aerobatic capability with cross-country efficiency in a package that amateur builders could complete in their garages. Its all-metal construction, proven Lycoming engine installations (typically 150-180 hp), and docile handling made it the template for the entire RV series that followed.

The type pioneered the concept of a "serious" homebuilt: an aircraft that could outperform many certified designs while remaining accessible to first-time builders. With a cruise speed around 180 knots and a roll rate exceeding 120 degrees per second, the RV-4 delivered fighter-like agility at a fraction of the cost. Though production plans ceased in 2003 when Van's shifted focus to the side-by-side RV-6 and later models, the RV-4 remains highly regarded in the experimental aircraft community for its honest aerobatic manners and efficient cross-country performance.

Its tandem seating and narrow fuselage give it a distinctly military aesthetic that appeals to builders seeking a sportier cockpit experience than the RV-6's side-by-side configuration offers. SkyMeter has tracked flights across airframes and operators, with the largest observed operator.

FLIGHTS
102
all time
FLOWN HOURS
38
tracked time
📍
AIRPORTS VISITED
18
unique
📡
CALLSIGNS
1
23 routes
📅
SERVICE PERIOD
06/03/2025 → 08/27/2026
first → last
INCIDENT RATE
19.6%
20 flagged

Top routes

By flight count

10
9
8
3
2
2
2
KHYI E70
1
1
1

Flight numbers

Most-flown by this airframe

1

Aircraft specifications

Van's Aircraft RV-4

Engines
Single Piston
Vref (approach)
65 kt
MTOW
1,500 lb
Wake category
L

Recent flights

Newest 50 operations of N39KW

50
08/27/2026
54m
No alerts
08/19/2026
10m
No alerts
08/19/2026
30m
No alerts
08/08/2026
24m
No alerts
07/02/2026
16m
No alerts
07/02/2026
55m
No alerts
06/20/2026
14m
△ Low approach-stability score
06/20/2026
15m
△ Low approach-stability score
06/12/2026
1h 0m
No alerts
06/12/2026
8m
No alerts
05/12/2026
1h 26m
No alerts
11/16/2025
19m
No alerts
11/16/2025
22m
No alerts
11/08/2025
15m
△ Low approach-stability score
11/08/2025
13m
△ Low approach-stability score
11/05/2025
22m
No alerts
11/05/2025
20m
No alerts
11/03/2025
16m
△ Low approach-stability score
11/03/2025
16m
△ Low approach-stability score
11/02/2025
21m
No alerts
11/02/2025
17m
△ Low approach-stability score
10/26/2025
13m
No alerts
10/17/2025
17m
No alerts
10/17/2025
19m
No alerts
10/13/2025
16m
No alerts
10/13/2025
14m
No alerts
10/03/2025
21m
No alerts
10/03/2025
21m
No alerts
10/03/2025
22m
△ Low approach-stability score
10/03/2025
22m
No alerts
09/26/2025
14m
No alerts
09/26/2025
13m
No alerts
09/21/2025
17m
No alerts
09/21/2025
19m
No alerts
09/12/2025
24m
No alerts
09/08/2025
14m
△ Low approach-stability score
09/08/2025
16m
No alerts
09/05/2025
22m
No alerts
09/05/2025
22m
No alerts
09/02/2025
40m
No alerts
08/26/2025
14m
No alerts
08/26/2025
50m
No alerts
08/19/2025
14m
△ Low approach-stability score
08/19/2025
13m
No alerts
08/18/2025
18m
No alerts
07/07/2025
16m
No alerts
07/07/2025
17m
No alerts
06/28/2025
12m
No alerts
06/20/2025
16m
No alerts
06/20/2025
15m
No alerts
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