- "Marty leaned forward [in the passenger seat of the DeLorean], trying to get a better view of the rain-swept sky. Yeah, there were lane markers out there, small orange cones simply floating in the air."
- —From Back to the Future Part II by Craig Shaw Gardner (quote, page 13)
- "They [Doc, Marty and Jennifer] were suddenly surrounded by flying cars that didn't look all that different from the DeLorean. They must be down in the non-commercial air lanes now. The cars seemed to be going much too fast in all this rain, but then, Marty realized, there weren't any roads to slip on any more, were there?"
- —From Back to the Future Part II by Craig Shaw Gardner (quote, pages 14 and 15)
A skyway was similar to a highway, with airspace set aside for the general public to drive flying vehicles.
Signs and lane markers for the skyways floated in the sky; how, exactly, these remained in the air is unknown, whether it be by antigravity mechanisms or magnetism, but no thrust was involved. Skyways were constructed throughout the planet sometime after 1985, and were in full operation in 2015. Local skyways connected to hyperlanes with access to major international cities on other continents. The hyperlane closest to Hill Valley, Hyperlane Grid 4, offered access to Phoenix, Boston and London.
Floating skyway signs would indicate exits, destinations, and even travel conditions for the skyway — including winds, weather and even ozone. A similar and smaller sign of the non-floating variety marked SKYWAY CONDITION was also present in Courthouse Square, where it was affixed to the corner of a rooftop and gave current travel conditions as "SKEWED ON".
In the novelization, air traffic controllers were employed to actively monitor the skyways to notify drivers of infractions of air traffic laws. All flying cars were equipped with transponders to help computers regulate the flow of traffic and for controllers to contact drivers to notify them of infractions. Other standard equipment for flying vehicles were eyewear that gave live video feed behind the vehicle to the driver and a communications headset.
After departing from Lyon Estates in 1985, the DeLorean appeared in the middle of Skyway C25 in 2015, but in the wrong lane and facing oncoming traffic. Doc had to lie to an air traffic controller about a broken transponder to cover for this mistake. There were separators between the lanes, and these could move if necessary to avoid a collision, albeit returning to a fixed location in the sky. Doc brought the vehicle down, under the lane markers, and back up again into the right lane. Upon reaching the exit 'ramp' that spiralled down into Courthouse Square, Doc landed the car in an alley. The skyway was visible from the square after the scheduled rain showers ended.
Same-way traffic seems to have flowed in multiple imaginary boxes one on top of each other. The equivalent of a traffic jam was if the skyway was "skewed", with traffic being unable to move in any direction — forward, backward, up or down. On October 21, 2015, the skyway from the Courthouse Mall to Hilldale was skewed, and even after departing during daylight, travelers that evening (namely Officers Reese and Foley of Unit N11-11, Doc and Marty, and a taxicab ferrying Biff) were not able to reach Hilldale until after dark.
After Marty and Doc carried Jennifer from the house in Hilldale, they prepared to return to the past, unaware that Biff had altered history. It appears that speeds were very fast on the skyway, at least 80 miles per hour, as Doc had to accelerate only slightly in order to reach 88 miles per hour when traveling from 2015 to 1985A. Whether the blinding flash from time displacement, or the remaining fire trails, had any effect on traffic in 2015, is unknown. When the DeLorean arrived back in 1985A, it was at an altitude that placed it slightly below the flight path of a descending commercial airliner.
Behind the scenes
- The floating skyway sign at the Hill Valley exit 'ramp' reads as follows: HYPERLANE - GRID 4 RN... [Rain] 20% VIS [Visibility] / PHOENIX : BOSTON : LONDON / LOCAL TRFC [Traffic] HILL VALLEY EXIT NEXT RIGHT.
- The SKYWAY CONDITION sign in Courthouse Square reads as follows: SKEWED ON / OZONE:10.5% ☼ [sun weather symbol, as here] W → SSE / H45.6% BP428 AZ48 VT6.
- In the novelization, the lane markers of the skyway are "small orange cones" (see first Quote above), rather than the illuminated versions seen on-screen.
- At the moment, the nearest thing we have to skyways is controlled airspace monitored by air traffic control directing aircraft both there and on the ground. Also, floating signs, lane markers etc. like those seen in Back to the Future Part II have yet to be invented.