The Collaborative International Dictionary of English v.0.48:

Planless \Plan"less\, a.
   Having no plan.
   [1913 Webster]

WordNet (r) 3.0 (2006):

planless
    adj 1: aimlessly drifting [syn: adrift(p), afloat(p),
           aimless, directionless, planless, rudderless,
           undirected]

Moby Thesaurus II by Grady Ward, 1.0:

52 Moby Thesaurus words for "planless":
   aimless, amorphous, capricious, casual, desultory, disarticulated,
   discontinuous, disjunct, disordered, dispersed, disproportionate,
   erratic, fitful, formless, frivolous, gratuitous, haphazard,
   hit-or-miss, immethodical, inchoate, incoherent, indiscriminate,
   irregular, meaningless, misshapen, nonsymmetrical, nonsystematic,
   nonuniform, orderless, promiscuous, random, senseless, shapeless,
   spasmodic, sporadic, straggling, straggly, systemless, unarranged,
   unclassified, undirected, ungraded, unjoined, unmethodical,
   unordered, unorganized, unsorted, unsymmetrical, unsystematic,
   ununiform, vague, wandering