  We have analyzed {\it Rossi X-ray Timing Explorer} (RXTE) data of the neutron
star transient Aquila X-1 obtained during its outbursts in May/June 1999 and
September/October 2000. We find that in the early rise of these outbursts, a
hard flare in the energy range above 15 keV preceded the soft X-ray peak. The
hard X-ray flux of the hard flares at maximum was more than a factor of three
stronger than at any other point in the outbursts. The rise of the hard X-ray
flare to this maximum, was consistent with a monotonically brightening low/hard
state spectrum. After the peak of the hard flare, a sharp spectral transition
occurred with spectral pivoting in the range 8--12 keV. Our timing analysis
shows that during the hard flare the power spectra were mainly composed of
band-limited noise and a $\sim$ 1--20 Hz QPO, which correlate in frequency.
Immediately after the hard flare, the power spectra turned into power law
noise. The spectral and timing properties during and after the hard flares are
very similar to those in black hole transients during the early rise of an
outburst. We suggest that these hard flares and spectral transitions in Aql X-1
are of the same origin as those observed in black hole transients. This leads
to the association of the 1--20 Hz QPOs and band-limited noise in Aql X-1 with
those in black hole transients. We discuss the impact of this discovery on our
understanding of soft X-ray transient outbursts, state transitions and
variability in X-ray binaries.
