Watsonville midair

[DaveReidUK]

Originally Posted by jimjim1

I have no idea where they get the data. I notice that Dave mentions Radar, however other discussion groups mention a different adsb radio frequency than used by "airline" grade (let me call it:-) adsb. There is certainly accurate looking height data. I think you can get that from a radar transponder.

Someone said:- "The C152 was pinging on 978mhz.

978 MHz is a reference to UAT (Universal Access Tranceiver) - an alternative (in the USA) to the more common 1090 MHz Extended Squitter. For either to be used for ADS-B (i.e. tracking) requires the aircraft to be equipped (usually) with a GPS source. Whether or not fitted with GPS, the aircraft will still send altitude data via Mode C or Mode S.

A number of the services we commonly use like FlightAware can't see 978 signals unless the plane is closer to 1800' in the Watsonville area"

Don't confuse what's available to crowd-sourced tracking sites like FlightAware or FR24 with what ATC (and hence the NTSB) has access to.

[Si Guy]

Thanks for your replies. I did some Googling from your comments, and I see that there are indeed two ADSB-out frequencies in use, 978 and 1090. Well, that’s certainly interesting. And maybe the C150 was too low to be received by the open-source receivers in the area. I was not aware there were multiple frequencies.

The Webtrak site is interesting, seems to be able to track both frequencies, but that site is not available over the whole country.

Thanks!

[DaveReidUK]

Originally Posted by Si Guy

The Webtrak site is interesting, seems to be able to track both frequencies, but that site is not available over the whole country.

SJC WebTrak is driven principally by radar data.

[Si Guy]

DaveReidUK - Ok, thanks. Been reading about it some more, seems it was primarily designed to allow for filing of noise complaints around major and medium size airports. But I can see it's useful for historical flight tracking as well.

[BFSGrad]

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The failure of the pilot of the multi-engine airplane to see and avoid the single-engine airplane while performing a straight-in approach for landing.

NTSB Aviation Investigation Final Report - N49931, N740WJ

[Andrewgr2]

I guess we’ll never know why the twin was doing 180 kts at 150’ on short final with gear and flaps up. If it hadn’t hit the light single it would have had an interesting landing.

[Maoraigh1]

"I guess we’ll never know why the twin was doing 180 kts at 150’ on short final with gear and flaps up."
Going Around?

[KRviator]

Originally Posted by Maoraigh1

"I guess we’ll never know why the twin was doing 180 kts at 150’ on short final with gear and flaps up."
Going Around?

That implies he intended to land. Something I'd suggest wasn't going to happen while maintaining 180 knots all the way down final without ever putting the gear or flaps out in the first place.

[BFSGrad]

Originally Posted by KRviator

That implies he intended to land.

Given that 740WJ called “straight in, 20, full stop” at 3 miles and one mile with no subsequent calls changing this plan, seems reasonable for others in the traffic pattern to conclude that he intended to land.