Are you really
sure about this?
There are a lot of countries that are using road bases just as the Ukrainians are doing now.
Among those countries are Australia, Finland, Germany, Japan, South Korea, Switzerland, Taiwan, the US and Sweden.
Japan and South Korea has the F-15. Taiwan has the F-16. And Japan also has the Mitsubishi F-2, which as I understand it is basically another F-16. If I'm not mistaken the F-16 can be equipped with a drogue chute. And the F-15 has a large dorsal air brake that can be deployed in flight when landing before the main gear has touched the ground.
Source:
en.wikipedia.org
Straight roads can be used to operate aircraft and as the link says, it's been done many times, but while US fighters are extremely good aircraft, they require facilities for maintenance and one drawback of western fighters is most are vulnerable to FOD (Foreign Object Damage).
The Soviets designed their fighters with the engine inlets either up on top of the plane or with taxi inlets that open on the ground. This enabled them to operate on fields with debris scattered on the taxiways and runways, which happens when airfields are attacked. Western fighters all have the inlets on the bottom or sides where they can ingest debris. It's common practice on western airfields to train personnel to be constantly diligent about finding and removing debris. I've been to open houses at US air bases where there were signs everywhere reminding people about FOD.
A highway can be kept clear of debris just like a dedicated runway, but the aircraft can only move under their own power on paved surfaces. Trying to park them in woods along the side of the road and firing them up there would only invite ingesting rocks, leaves, and other forest objects.
The facilities to maintain the aircraft have to be located somewhere near where they are operating. That means some kind of permanence to the basing. Forward bases where aircraft have their fuel tanks topped up and/or quickly reloaded with munitions can be established with maintenance bases to the rear, but I don't see where they would do the Ukrainians much good in this conflict.
Ukraine is large for a European country, but is fairly small for a modern jet fighter. The Soviet era fighters the Ukrainians have now are shorter range than US fighters and the Ukrainians haven't done any forward basing I'm aware of.
In any case, there will have to be some kind of established bases for the fighters. Even if it's some co-opted highway, there needs to be facilities to support the aircraft. As soon as the bases are established, the Russians will be trying to take them out.
I did come across some further information about the pilot training. It not only hasn't started yet, it hasn't made it to Biden's desk yet. The bill has just passed the House and won't be taken up by the Senate until September
Slava Ukraine! US Approves To Train Ukrainian Pilots On US Fighter Jets Like F-16, F-15EX. But There's A Catch
Ukraine will be lucky to get US fighters in action by early next year.
I expect that after the war is over Ukraine will be switching to a completely NATO compatible equipment list. With the lessons learned from this war, seamless integration with NATO supply chains, and other factors, Russia will probably never come knocking again. Ukraine will be just too tough to even contemplate.
Plus the Russian army will be broken for at least a few decades after this. It's going to take them a long time to rebuild what institutional knowledge they had and was lost when they threw their last expert into the fire. Depending on how Russia tries to recover from this war and what happens within Russia in the aftermath, it may be the end of the Russian army as an effective fighting force forever.