Disconcerting

Adjective

 * 1) Tending to cause discomfort, uneasiness or alarm; unsettling; troubling; upsetting.
 * Even with a safety harness, losing one's grip that high up is disconcerting.

Thesaurus
alarming, awing, awkward, baffling, bewildering, bothering, chilling, confounding, confusing, crushing, daunting, defeating, deterrent, deterring, discomposing, discouraging, disheartening, dismaying, disquieting, distracting, disturbing, embarrassing, enigmatic, fear-inspiring, fearful, fearsome, frightening, frightful, frustrating, humiliating, intricate, mortifying, mysterious, mystifying, overawing, perplexing, perturbing, problematic, puzzling, scaring, scary, startling, unsettling, upsetting