What is the maximum permissible slope for a table top Runway (elevation 1600 m) to be made on hill top ?
Most Part-25 certified aircraft have an operating limit of roughly +/-2% for runway slope, as most of the runways fall into this category.
It would be probably possible to certify aircraft for steeper slopes, however at a significant cost, as the flight test program would have to be extended to collect sufficient data.
It is also worth mentioning that anything over 1% upslope requires a bit of a different flare technique as opposed to a flat runway. Usually a bit earlier flare with a bit late thrust reduction does the trick. Extending the limit beyond 2% would probably require additional training, as the flare characteristics would be significantly different than that at a normal runway.