Speed Ground Ual175, Le calcul des vitesses par le NTSB Options

[tournesol01]

Bonjour.

Y a t'il quelqu'un pour parler en français et me traduire. C'est pour exposer mes travaux sur l'étude des données radar de Newark.

Je trouve qu'elles peuvent être plus basses que cela a été écrit par le NTSB.

[tournesol01]

Good morning.

Is there someone to speak French and translate for me. This is to expose my work on the study of radar data Newark.

I think they may be lower than it was written by the NTSB.

I have to go through translate.google.fr and it is very long for me.

[tournesol01]

Here is what I propose as speed curve:

[tournesol01]

I would like to have the opinion who the next person is a member of your association:

Hammish Brannan
Former United Kingdom air defense ground enviroment (UKADGE) RADAR technician
Primary and secondary ground radar systems
ATC & airborne systems (including radio) as an instructor for the Ministry of Defence (MOD)

[tournesol01]

I will begin to explain my point of view:

On the bottom graph are red dots. These are the values ​​of ground speeds calculated from the raw radar data Newark (EWR)
Vertical dispersion of these points is elevated when they should be follow up with more regularity, not zigzagging. A plane takes time to change gear.

Where does this dispersion? On the one error of less than 1 degree on the azimuth of the radar blips.

Playing on the value of the azimuth replace the radar blips in a better configuration and allows to obtain a curve closer to reality speed (the blue dots)

Speeds are reduced.
Altitude and Range remain the same.

The downward slope of the altitude of ual175 flight is nearly constant.

Finally, the pilot pushed the engine a short time before impact.
Then he may have slowed for the aircraft is not disintegrated before impact.

This is my own belief, what do you think of that ?

This post has been edited by tournesol01: Apr 3 2014, 11:37 AM

[rob balsamo]

I will begin to explain my point of view:

On the bottom graph are red dots. These are the values ​​of ground speeds calculated from the raw radar data Newark (EWR)

Those look pretty accurate. I calculated similar results with the RADES data.... it shows the aircraft exceeding 500 knots with values as high as 540 for roughly the last 3 minutes of flight.

The NTSB is correct with regard to the speeds reported. Keep in mind, they also used radar from JFK, LGA, and HPN... and also did a Video Speed study with similar results.

[tournesol01]

The speed curve NTSB is not the same as I got with excel. Have you also tried to reconstruct these curves?

[rob balsamo]

The speed curve NTSB is not the same as I got with excel. Have you also tried to reconstruct these curves?

No, I calculated the speeds using Lat/long positions of the RADES data. The results are similar to the raw EWR data you have plotted above. However, the end of your curve is not accurate and does not reflect the raw data you have plotted.

Again, keep in mind, the NTSB used more than just EWR radar for the speed study.

[tournesol01]

That's what scares me!

Why do not they trust a single radar?

With excel I recalculated the latitudes and longitudes of the studs EWR and I did not detect significant difference.

[rob balsamo]

That's what scares me!

Why do not they trust a single radar?

The NY Terminal area is a very busy place serving 6-7 very busy airports in close proximity. Speeds are being assigned to aircraft daily, in real time, so they don't run into each other. I certainly feel very comfortable having more than one radar looking at my airplane when getting vectored for an approach into LGA, JFK, EWR, TEB, HPN... or transitioning to FRG or MMU.

[tournesol01]

No, I calculated the speeds using Lat/long positions of the RADES data. The results are similar to the raw EWR data you have plotted above. However, the end of your curve is not accurate and does not reflect the raw data you have plotted.

The last plot of radar data is an estimate plot because he had no primary radar (BO).
His position may have some margin.

[tournesol01]

The NY Terminal area is a very busy place serving 6-7 very busy airports in close proximity. Speeds are being assigned to aircraft daily, in real time, so they don't run into each other. I certainly feel very comfortable having more than one radar looking at my airplane when getting vectored for an approach into LGA, JFK, EWR, TEB, HPN... or transitioning to FRG or MMU.

yes but the question is why the NTSB not only the nearest radar for its calculations?

[rob balsamo]

yes but the question is why the NTSB not only the nearest radar for its calculations?

They did. The aircraft was moving... so certainly JFK ASR would be useful... along with the other radar facilities in the NY Terminal Area.

We are talking about roughly a 30 mile radius around the WTC... many/all of the radar in this area are used to assign speeds to thousands of aircraft per day.

And again, the NTSB went even further and did a Video speed study which produced similar results to their radar study.

The more data you have, the more accurate the results... yes?

[tournesol01]

The last plot of radar data is an estimate plot because he had no primary radar (BO).
His position may have some margin.

The calculations are done with Excel, the formulas are the same for all plots.
There is no reason for the last blocks are worse than others.

If there is someone you good at math and Excel, I want to share my Excel file and discuss my results and my possible mistakes.

[rob balsamo]

If there is someone you good at math and Excel, I want to share my Excel file and discuss my results and my possible mistakes.

Upload it to a host and feel free to post it.... I'm sure someone may take a look at it. I will when I have the time....

[tournesol01]

They did. The aircraft was moving... so certainly JFK ASR would be useful... along with the other radar facilities in the NY Terminal Area.

We are talking about roughly a 30 mile radius around the WTC... many/all of the radar in this area are used to assign speeds to thousands of aircraft per day.

And again, the NTSB went even further and did a Video speed study which produced similar results to their radar study.

The more data you have, the more accurate the results... yes?

For the final leg I see only two radars, JFK and EWR.
I do not know others.

For videos, there where the plane is nearer and I think the speed is therefore more accurate.

[tournesol01]

Upload it to a host and feel free to post it.... I'm sure someone may take a look at it. I will when I have the time....

OK

I put clean before !

[tournesol01]

Speed UAL175

You can adjust the curve by putting values ​​in the "adjust" column

Mine are in red in the next column, you can copy them.

[tournesol01]

Excel Speed UAL175

You can adjust the curve by putting values ​​in the "adjust" column

Mine are in red in the next column, you can copy them.

[tumetuestumefais...]

I'm also quite not sure about the end of the curve. The impact speed - as multiple radar analyses and also multiple video analyses (see here, here, here and here) show was quite definitely higher than 470 kts.

If you want to discus this in French, you can contact me via PM - I would think it will be better to keep this forum here in international aviation language - the English.
Si tu veux discuter ca en français, tu peux me contacter par PM - Je pense que ca sera mieux tenir cet forum ici en la lague de l'aviation internationale - L'anglais