The three-dimensional modal linear stability analysis is performed for the near-wall flow of a full-scale generic hypersonic vehicle forebody at flight Mach numbers 4, 6, and 8, at different angles of attack. The mean flow is computed with a Navier-Stokes commercial code. A physically sound, computationally efficient original method is proposed to define the integration path in the e N method. It has a significant impact on the computed N factors. The entropy-layer effect on the flow instability is analyzed in the framework of Lees and Lin's asymptotic theory. The entropy layer introduces an additional unstable mode, for which N 4. Results show that crossflow instability is dominant at Mach 6 and 8, whereas Mack's oblique first mode prevails at Mach 4. This mode is stabilized by a radiating wall, compared with an adiabatic one. Mack's second mode is also present at Mach 8. In any case, none of the instability modes that have been found is strong enough to provoke a natural transition in flight by itself: computed N factors do not exceed 10. Attempts to correlate the results with the Re =M e Const criterion are discussed.Nomenclature a = speed of sound, m=s C p , = heat capacity at constant pressure, J=kg K C v = heat capacity at constant volume, J=kg K f = frequency, Hz h = enthalpy per unit mass, J=kg k = thermal conductivity, W=m K k = wave vector (real), 1=m P = pressure, Pa r = C p C v , gas constant, J=kg K T = temperature, K t = time, s U, V, W = mean-flow components along x, y, and z, m=s V g = group velocity vector, m=s V ' = phase velocity, m=s W = molecular weight of species , kg=kmol X, Y, Z = coordinates in the global reference frame attached to the vehicle, m x, y, z = streamwise, transverse (normal to the wall), and spanwise coordinates, m X = mole fraction of species , = wave numbers (complex) in the x and z directions, 1=m = displacement thickness, m = momentum thickness, m g = direction of V g = viscosity, kg=m s = =, diffusivity, m 2 =s = density, kg=m 3 = amplification vector (real), 1=m = compressibility factor = direction of k = direction of ! = (real) pulsation, 1=sSubscripts M = maximum value (envelope method) u = unity w = value at the wall 1 = value at infinity, static value Superscripts e = value in the freestream, outside the boundary layer N = exponent in the e N method