GST From United Kingdom, joined Jun 2008, 939 posts, RR: 0
Reply 2, posted (3 years 1 month 3 weeks 4 days 21 hours ago) and read 5402 times:
Very impressive indeed. Two things have me confused though, and I'm interested to see sources for some of the figures so I can rest assured it is me being an idiot.
Quote: The Q400 NextGen is the only commercial turboprop available today to make use of the (ANVS) system, with which the average cabin noise of 77-79dBA is lower than that in an Airbus A318/319, and around 2-4dB quieter than the ATR72′s cabin.
Now correct me if I am wrong, but with decibels being a logarithmic scale an increase in 10 decibels means a doubling of perceived "loudness" to the human ear. So 77-79dB increase is ~200 times as loud?!?! I am quite happy to accept my thought process being flawed here but I wonder if this is a case of forgetting to add a decimal point into the numbers?
Secondly fuel consumption.
Quote: Performance aside, for an ATR72 and a Q400 flying 9 flights a day, the Q400 lands up consuming 985,000kgs extra fuel more than an ATR72, this translating to around INR 4.5Cr in today’s value of ATF for turboprops.
Any idea how long a time this fuel consumption difference is estimated over? Or should it be 985kg? Again I'm willing to accept the mistake as being mine, or to have overlooked some critical info.
Fabo From Slovakia, joined Aug 2005, 1219 posts, RR: 1
Reply 3, posted (3 years 1 month 3 weeks 3 days 10 hours ago) and read 5058 times:
Quoting GST (Reply 2): So 77-79dB increase is ~200 times as loud?!?!
The level is 77-79dB, that being about 2-4dB less than ATR, and unspecified amount less than A319.
Quoting GST (Reply 2): Any idea how long a time this fuel consumption difference is estimated over? Or should it be 985kg? Again I'm willing to accept the mistake as being mine, or to have overlooked some critical info.
That would be per year, although the methodology behind the number is not truly correct (no airplane flies 9 legs a day, every day, even weekends, national holidays etc)
The light at the end of tunnel turn out to be a lighted sing saying NO EXIT
prebennorholm From Denmark, joined Mar 2000, 6661 posts, RR: 54
Reply 4, posted (3 years 1 month 3 weeks 3 days 5 hours ago) and read 5007 times:
Quoting Fabo (Reply 3): ...the methodology behind the number is not truly correct (no airplane flies 9 legs a day, every day, even weekends, national holidays etc)
Incorrect. ATR-42 and -72 operate the bulk of domestic route in my (tiny) country. Routes are like a six armed star with CPH as hub, and route lengths vary between 100 and 130nm = scheduled flight times being 40 to 50 minutes with turnarounds being 20 minutes-ish. Slightly longer turnaround when fueling is needed, but they fly several sectors after being fueled.
They all produce way more than 9 legs a day from early morning to almost midnight.
Every day, also weekends and holidays when roughly half of the fleet is parked and frequency is correspondingly reduced.
At least until Sunday at noon. Sunday afternoon/evening is quite busy since businesmen/-women need to be in place Sunday night for meetings all over Europe (etc.) early Monday morning, and the domestic routes are to a large extent feeders to international traffic out of CPH.
Tell Cimber Air that they shall only be allowed to fly 9 sectors a day with each plane, and they will be very disappointed. Me too, since I need their service quite frequently.
Always keep your number of landings equal to your number of take-offs, Preben Norholm