The exchange above is interesting to any student of HF and vhf propagation.
I think the experts like Roger VK2ZRH would suggest that E layer propagation is more common on HF than is usually thought. It is even observed to affect propagation on 3.5 MHz, with deep QSB occurring on normally stable paths, due to interference between the E path and the more typical (higher) F layer path.
As I understand it, the spE reflections, like F layer, are frequency sensitive in their behaviour. They are also dependent on the angle of incidence. Depending on the density of the ionisation at the E layer, they may support propagation at up to 30 MHz, or up to 60 MHz (which 6m fans enjoy) or even up to 160 MHz (2m ops go nuts).
The observation of a specific distance on 14 MHz usually indicating a spE density that will also support VHF propagation is probably justified, however a more general observation of “any spE” on HF does not necessarily indicate any specific upper frequency limit.
Eg your usual observed 14 MHz lower limit to supported F layer propagation may be say 1000 km. When a station is heard at a distance of 800 km, that indicates some additional path is present, so propagation via spE may be extending up to 40 MHz. When the distance on 14 MHz drops to 600 km, this may indicate spE up to 80 MHz. At 400 km, it may be 120 MHz. At 200km, it indeed could be as high as 150 MHz. All numbers for illustration only.
So I would support Phil’s observation of a specific short distance on 14 MHz indicating predictable propagation on various vhf bands, while also agreeing with Richard’s general comment that 14 MHz spE is not a good indicator of 2m spE.
As usual, the devil is in the details.
73 Andrew VK1DA/VK2UH