Calc Skyrim - Odahviing flies Dovahkiin to Skuldafn

Odahviing flies from Whiterun to Skuldafn in an incredibly short time period (only 19 minutes by my own measuring). Previously, I calculated the distance between Riften and Solitude at being 594.024878km at a low end, 834.319526km at a mid end and 1251.47929km at a high end (using the unofficial interactive Skyrim map for help).
(Low end)
1216 pixels = 594.024878km
1 pixel = 594.024878km/1216 = 0.488507301km
0.488507301km X 667 = 325.83437km

(Mid end)
1216 pixels = 834.319526km
1 pixel = 834.319526km/1216 = 0.686118031km
0.686118031km X 667 = 457.640727km

(High end)
1216 pixels = 1251.47929km
1 pixel = 1251.47929km/1216 = 1.02917705km
1.02917705km X 667 = 686.461092km
The journey takes 19 minutes.

T = 60 X 19
= 1140s

At last, we can find out how fast Odahviing flew!

(Low end)
T = 325.83437km/1140s
= 285.819623m/s

(Mid end)
T = 457.640727km/1140s
= 401.439234/340.29
= Mach 1.17969742

(High end)
T = 686.461092km/1140s
= 602.158853/340.29
= Mach 1.76954613

Final Results
Odahviing flies Dovahkiin to Skuldafn (low end) = 285.82m/s
Odahviing flies Dovahkiin to Skuldafn (mid end) = Mach 1.18
Odahviing flies Dovahkiin to Skuldafn (high end) = Mach 1.77